diff --git a/DESCRIPTION b/DESCRIPTION
index 786e11e..df70007 100755
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -3,8 +3,8 @@ Type: Package
 Title: Sequential Pairwise Online Rating Techniques
 Version: 0.2.1
 Depends: R (>= 3.0)
-Authors@R: person("Dawid", 
-                  "Kałędkowski", 
+Authors@R: person("Dawid",
+                  "Kałędkowski",
                   email = "dawid.kaledkowski@gmail.com",
                   comment = c(ORCID = "0000-0001-9533-457X"),
                   role = c("aut", "cre"))
@@ -17,15 +17,15 @@ Description: Calculates ratings for two-player or
   Parameters are updated sequentially, and computation doesn't require any 
   additional RAM to make estimation feasible. Additionally, base of the package 
   is written in C++ what makes sport computation even faster. Methods used in the 
-  package refers to Mark E. Glickman (1999) 
+  package refer to Mark E. Glickman (1999) 
   <http://www.glicko.net/research/glicko.pdf>; 
   Mark E. Glickman (2001) <doi:10.1080/02664760120059219>; 
   Ruby C. Weng, Chih-Jen Lin (2011) <https://www.jmlr.org/papers/volume12/weng11a/weng11a.pdf>; 
   W. Penny, Stephen J. Roberts (1999) <doi:10.1109/IJCNN.1999.832603>.
 BugReports: https://github.com/gogonzo/sport/issues
 Imports: 
-  Rcpp, 
-  data.table, 
+  Rcpp,
+  data.table,
   ggplot2
 LinkingTo: Rcpp
 License: GPL-2
@@ -37,8 +37,8 @@ RoxygenNote: 7.2.3
 Roxygen: list(markdown = TRUE)
 Suggests: 
   dplyr,
-  knitr, 
+  knitr,
   lobstr,
-  rmarkdown, 
+  rmarkdown,
   testthat
 VignetteBuilder: knitr
diff --git a/vignettes/the_theory.Rmd b/vignettes/the_theory.Rmd
index a28f6f4..ed936f5 100644
--- a/vignettes/the_theory.Rmd
+++ b/vignettes/the_theory.Rmd
@@ -245,7 +245,7 @@ dbl <- dbl_run(
 print(dbl$final_r)
 ```
 
-For more details read [Stephen J. Roberts, William Penny (2011)](https://www.researchgate.net/publication/2465226_Dynamic_Logistic_Regression)
+For more details read [Stephen J. Roberts, William Penny (2011)](https://doi.org/10.1109/IJCNN.1999.832603)
 
 
 ## Additional controls