diff --git a/R/soilColorIndices.R b/R/soilColorIndices.R
index 09286132d..a8a8adfb8 100644
--- a/R/soilColorIndices.R
+++ b/R/soilColorIndices.R
@@ -1,13 +1,14 @@
 # miscellaneous soil color indices
 
 #' @title Horizon Color Indices
-#' @description Calculate basic horizon-level color indices for a SoilProfileCollection. Basic indices do not require aggregation over the whole profile or comparison to a "reference" (e.g. parent material) color. Includes Hurst (1977) Redness Index, Barron-Torrent Redness Index (1986) and Buntley-Westin Index (1965).
+#' @description Calculate basic horizon-level color indices for a SoilProfileCollection. Basic indices do not require aggregation over the whole profile or comparison to a "reference" (e.g. parent material) color. Includes Hurst (1977) Redness Index, Barron-Torrent Redness Index (1986) and Buntley-Westin Index (1965). This is a wrapper method around several horizon-level indices. See the individual functions for more details.
 #' @param p A SoilProfileCollection
 #' @param hue Column name containing moist hue; default: "m_hue"
 #' @param value Column name containing moist value; default: "m_value"
 #' @param chroma Column name containing moist chroma; default: "m_chroma"
 #' @return A data.frame containing unique pedon and horizon IDs and horizon-level color indices.
 #' @author Andrew G. Brown.
+#' @seealso \code{\link{hurst.redness}} \code{\link{barron.torrent.redness.LAB}} \code{\link{buntley.westin.index}} 
 #' @examples
 #' data(sp1)
 #'
@@ -47,6 +48,7 @@ horizonColorIndices <- function(p, hue="m_hue", value="m_value", chroma="m_chrom
 #' @param chroma A numeric vector containing Munsell chromas
 #' @return A numeric vector of horizon redness index (lower values = redder).
 #' @author Andrew G. Brown.
+#' @references Hurst, V.J. (1977) Visual estimation of iron in saprolite. GSA Bulletin. 88(2): 174–176. doi: https://doi.org/10.1130/0016-7606(1977)88<174:VEOIIS>2.0.CO;2
 #' @rdname hurst.redness
 #' @export hurst.redness
 hurst.redness <-  function(hue, value, chroma) {
@@ -66,6 +68,7 @@ hurst.redness <-  function(hue, value, chroma) {
 #' @param chroma A numeric vector containing Munsell chromas
 #' @return A numeric vector of horizon redness index (higher values = redder).
 #' @author Andrew G. Brown.
+#' @references Barron, V. and Torrent, J. (1986), Use of the Kubelka—Munk theory to study the influence of iron oxides on soil colour. Journal of Soil Science, 37: 499-510. doi:10.1111/j.1365-2389.1986.tb00382.x
 #' @rdname barron.torrent.redness.LAB
 #' @export barron.torrent.redness.LAB
 barron.torrent.redness.LAB <- function(hue, value, chroma) {
@@ -83,6 +86,7 @@ barron.torrent.redness.LAB <- function(hue, value, chroma) {
 #' @param chroma_ref A numeric vector containing Munsell chroma(s) for reference material
 #' @return A numeric vector reflecting horizon redness increase relative to a reference (e.g. parent) material.
 #' @author Andrew G. Brown.
+#' @references Harden, J.W. (1982) A quantitative index of soil development from field descriptions: Examples from a chronosequence in central California. Geoderma. 28(1) 1-28. doi:  10.1016/0016-7061(82)90037-4
 #' @rdname harden.rubification
 #' @export harden.rubification
 harden.rubification <- function(hue, chroma, hue_ref, chroma_ref) {
@@ -101,6 +105,7 @@ harden.rubification <- function(hue, chroma, hue_ref, chroma_ref) {
 #' @param value_ref A numeric vector containingMunsell value(s) for reference material
 #' @return A numeric vector reflecting horizon darkening relative to a reference (e.g. parent) material.
 #' @author Andrew G. Brown.
+#' @references Harden, J.W. (1982) A quantitative index of soil development from field descriptions: Examples from a chronosequence in central California. Geoderma. 28(1) 1-28. doi:  10.1016/0016-7061(82)90037-4
 #' @rdname harden.melanization
 #' @export harden.melanization
 harden.melanization <- function(value, value_ref) {
@@ -115,8 +120,9 @@ harden.melanization <- function(value, value_ref) {
 #' @description Calculate "Color Development Equivalent" by the method of Buntley & Westin (1965) "A Comparative Study of Developmental Color in a Chestnut-Chernozem-Brunizem Soil Climosequence" DOI: 10.2136/sssaj1965.03615995002900050029x. Originally developed for Mollisols, the Buntley-Westin index has been used as a tool to separate soils based on depth to particular colors.
 #' @param hue A character vector containing Munsell hues (e.g. "7.5YR")
 #' @param chroma A numeric vector containing Munsell chromas
-#' @return A numeric vector reflecting horizon redness (higher values = redder).
+#' @return A numeric vector reflecting horizon color development.
 #' @author Andrew G. Brown.
+#' @references Buntley, G.J. and Westin, F.C. (1965), A Comparative Study of Developmental Color in a Chestnut‐Chernozem‐Brunizem Soil Climosequence. Soil Science Society of America Journal, 29: 579-582. doi:10.2136/sssaj1965.03615995002900050029x
 #' @rdname buntley.westin.index
 #' @export buntley.westin.index
 buntley.westin.index <- function(hue, chroma) {
@@ -135,8 +141,9 @@ buntley.westin.index <- function(hue, chroma) {
 #' @param pattern Regular expression to match A horizons (default: "^A" which means horizon designation _starts with_ A)
 #' @param value Column name containing horizon color values (default: "m_value")
 #' @param chroma Column name containing horizon color chromas (default: "m_chroma")
-#' @return A numeric vector reflecting horizon redness (higher values = redder).
+#' @return A numeric vector reflecting horizon darkness (lower values = darker).
 #' @author Andrew G. Brown.
+#' @references Thompson, J.A. and Bell, J.C. (1996), Color Index for Identifying Hydric Conditions for Seasonally Saturated Mollisols in Minnesota. Soil Science Society of America Journal, 60: 1979-1988. doi:10.2136/sssaj1996.03615995006000060051x
 #' @rdname thompson.bell.darkness
 #' @export thompson.bell.darkness
 thompson.bell.darkness <- function(p, name = NULL, pattern="^A", value="m_value", chroma="m_chroma") {
diff --git a/man/barron.torrent.redness.LAB.Rd b/man/barron.torrent.redness.LAB.Rd
index 70eeb98a3..d838e6096 100644
--- a/man/barron.torrent.redness.LAB.Rd
+++ b/man/barron.torrent.redness.LAB.Rd
@@ -19,6 +19,9 @@ A numeric vector of horizon redness index (higher values = redder).
 \description{
 Calculate Redness Index after Barron & Torrent (1986) "Use of the Kubelka—Munk Theory to Study the Influence of Iron Oxides on Soil Colour" using Munsell colors converted to LAB. DOI: 10.1111/j.1365-2389.1986.tb00382.x. Accepts vectorized inputs for hue, value and chroma, produces vector output.
 }
+\references{
+Barron, V. and Torrent, J. (1986), Use of the Kubelka—Munk theory to study the influence of iron oxides on soil colour. Journal of Soil Science, 37: 499-510. doi:10.1111/j.1365-2389.1986.tb00382.x
+}
 \author{
 Andrew G. Brown.
 }
diff --git a/man/buntley.westin.index.Rd b/man/buntley.westin.index.Rd
index 3cd5ff6b8..047016190 100644
--- a/man/buntley.westin.index.Rd
+++ b/man/buntley.westin.index.Rd
@@ -12,11 +12,14 @@ buntley.westin.index(hue, chroma)
 \item{chroma}{A numeric vector containing Munsell chromas}
 }
 \value{
-A numeric vector reflecting horizon redness (higher values = redder).
+A numeric vector reflecting horizon color development.
 }
 \description{
 Calculate "Color Development Equivalent" by the method of Buntley & Westin (1965) "A Comparative Study of Developmental Color in a Chestnut-Chernozem-Brunizem Soil Climosequence" DOI: 10.2136/sssaj1965.03615995002900050029x. Originally developed for Mollisols, the Buntley-Westin index has been used as a tool to separate soils based on depth to particular colors.
 }
+\references{
+Buntley, G.J. and Westin, F.C. (1965), A Comparative Study of Developmental Color in a Chestnut‐Chernozem‐Brunizem Soil Climosequence. Soil Science Society of America Journal, 29: 579-582. doi:10.2136/sssaj1965.03615995002900050029x
+}
 \author{
 Andrew G. Brown.
 }
diff --git a/man/harden.melanization.Rd b/man/harden.melanization.Rd
index 0097ab58b..a3bdc6ad2 100644
--- a/man/harden.melanization.Rd
+++ b/man/harden.melanization.Rd
@@ -17,6 +17,9 @@ A numeric vector reflecting horizon darkening relative to a reference (e.g. pare
 \description{
 Calculate Melanization component of Profile Development Index after Harden (1982) "A quantitative index of soil development from field descriptions: Examples from a chronosequence in central California". Accepts vectorized inputs for hue and chroma to produce vector output. In Harden (1982), melanization is calculated relative to a reference parent material for all horizons within 100cm of the soil surface. In addition, several other non-color components are normalized relative to a maximum value and summed to obtain the overall Profile Development Index.
 }
+\references{
+Harden, J.W. (1982) A quantitative index of soil development from field descriptions: Examples from a chronosequence in central California. Geoderma. 28(1) 1-28. doi:  10.1016/0016-7061(82)90037-4
+}
 \author{
 Andrew G. Brown.
 }
diff --git a/man/harden.rubification.Rd b/man/harden.rubification.Rd
index 256486437..13ed92275 100644
--- a/man/harden.rubification.Rd
+++ b/man/harden.rubification.Rd
@@ -21,6 +21,9 @@ A numeric vector reflecting horizon redness increase relative to a reference (e.
 \description{
 Calculate Rubification component of Profile Development Index after Harden (1982) "A quantitative index of soil development from field descriptions: Examples from a chronosequence in central California". Accepts vectorized inputs for hue, value and chroma to produce vector output. In Harden (1982) rubification is calculated relative to a reference parent material. Several other non-color components are normalized relative to a maximum value and summed to obtain the overall Profile Development Index.
 }
+\references{
+Harden, J.W. (1982) A quantitative index of soil development from field descriptions: Examples from a chronosequence in central California. Geoderma. 28(1) 1-28. doi:  10.1016/0016-7061(82)90037-4
+}
 \author{
 Andrew G. Brown.
 }
diff --git a/man/horizonColorIndices.Rd b/man/horizonColorIndices.Rd
index b5d728f5c..359d9e0ff 100644
--- a/man/horizonColorIndices.Rd
+++ b/man/horizonColorIndices.Rd
@@ -19,7 +19,7 @@ horizonColorIndices(p, hue = "m_hue", value = "m_value", chroma = "m_chroma")
 A data.frame containing unique pedon and horizon IDs and horizon-level color indices.
 }
 \description{
-Calculate basic horizon-level color indices for a SoilProfileCollection. Basic indices do not require aggregation over the whole profile or comparison to a "reference" (e.g. parent material) color. Includes Hurst (1977) Redness Index, Barron-Torrent Redness Index (1986) and Buntley-Westin Index (1965).
+Calculate basic horizon-level color indices for a SoilProfileCollection. Basic indices do not require aggregation over the whole profile or comparison to a "reference" (e.g. parent material) color. Includes Hurst (1977) Redness Index, Barron-Torrent Redness Index (1986) and Buntley-Westin Index (1965). This is a wrapper method around several horizon-level indices. See the individual functions for more details.
 }
 \examples{
 data(sp1)
@@ -40,6 +40,9 @@ plot(sp1, color='hurst_redness')
 plot(sp1, color='barron_torrent_redness')
 plot(sp1, color='buntley_westin')
 }
+\seealso{
+\code{\link{hurst.redness}} \code{\link{barron.torrent.redness.LAB}} \code{\link{buntley.westin.index}}
+}
 \author{
 Andrew G. Brown.
 }
diff --git a/man/hurst.redness.Rd b/man/hurst.redness.Rd
index 0064d0456..b0d13d9e3 100644
--- a/man/hurst.redness.Rd
+++ b/man/hurst.redness.Rd
@@ -19,6 +19,9 @@ A numeric vector of horizon redness index (lower values = redder).
 \description{
 Calculate Redness Index after Hurst (1977) "Visual estimation of iron in saprolite" DOI: 10.1130/0016-7606(1977)88<174:VEOIIS>2.0.CO;2. Accepts vectorized inputs for hue, value and chroma, produces vector output.
 }
+\references{
+Hurst, V.J. (1977) Visual estimation of iron in saprolite. GSA Bulletin. 88(2): 174–176. doi: https://doi.org/10.1130/0016-7606(1977)88<174:VEOIIS>2.0.CO;2
+}
 \author{
 Andrew G. Brown.
 }
diff --git a/man/thompson.bell.darkness.Rd b/man/thompson.bell.darkness.Rd
index e2accdb52..723eb1752 100644
--- a/man/thompson.bell.darkness.Rd
+++ b/man/thompson.bell.darkness.Rd
@@ -24,11 +24,14 @@ thompson.bell.darkness(
 \item{chroma}{Column name containing horizon color chromas (default: "m_chroma")}
 }
 \value{
-A numeric vector reflecting horizon redness (higher values = redder).
+A numeric vector reflecting horizon darkness (lower values = darker).
 }
 \description{
 Calculate the "Profile Darkness Index" by the method of Thompson & Bell (1996) "Color index for identifying hydric conditions for seasonally saturated mollisols in Minnesota" DOI: 10.2136/sssaj1996.03615995006000060051x. The Thompson-Bell Index has been shown to reflect catenary relationships in some Mollisols of Minnesota (generally: wetter landscape positions = thicker, darker surfaces).
 }
+\references{
+Thompson, J.A. and Bell, J.C. (1996), Color Index for Identifying Hydric Conditions for Seasonally Saturated Mollisols in Minnesota. Soil Science Society of America Journal, 60: 1979-1988. doi:10.2136/sssaj1996.03615995006000060051x
+}
 \author{
 Andrew G. Brown.
 }