diff --git a/src/FormNetworks/abstractformnetwork.jl b/src/FormNetworks/abstractformnetwork.jl
index a2749335..e23424ba 100644
--- a/src/FormNetworks/abstractformnetwork.jl
+++ b/src/FormNetworks/abstractformnetwork.jl
@@ -13,15 +13,14 @@ operator_vertex_suffix(f::AbstractFormNetwork) = not_implemented()
 bra_vertex_suffix(f::AbstractFormNetwork) = not_implemented()
 ket_vertex_suffix(f::AbstractFormNetwork) = not_implemented()
 
-bra(f::AbstractFormNetwork) = induced_subgraph(f, collect(values(bra_vertex_map(f))))
-ket(f::AbstractFormNetwork) = induced_subgraph(f, collect(values(ket_vertex_map(f))))
-function operator(f::AbstractFormNetwork)
-  return induced_subgraph(f, collect(values(operator_vertex_map(f))))
+function operator_vertices(f::AbstractFormNetwork)
+  return filter(v -> last(v) == operator_vertex_suffix(f), vertices(f))
 end
-
-function derivative(f::AbstractFormNetwork, state_vertices::Vector; kwargs...)
-  tn_vertices = derivative_vertices(f, state_vertices)
-  return derivative(tensornetwork(f), tn_vertices; kwargs...)
+function bra_vertices(f::AbstractFormNetwork)
+  return filter(v -> last(v) == bra_vertex_suffix(f), vertices(f))
+end
+function ket_vertices(f::AbstractFormNetwork)
+  return filter(v -> last(v) == ket_vertex_suffix(f), vertices(f))
 end
 
 function bra_vertices(f::AbstractFormNetwork, state_vertices::Vector)
@@ -32,6 +31,26 @@ function ket_vertices(f::AbstractFormNetwork, state_vertices::Vector)
   return [ket_vertex_map(f)(sv) for sv in state_vertices]
 end
 
+function Graphs.induced_subgraph(f::AbstractFormNetwork, vertices::Vector)
+  return induced_subgraph(tensornetwork(f), vertices)
+end
+function bra(f::AbstractFormNetwork)
+  return rename_vertices(inv_vertex_map(f), first(induced_subgraph(f, bra_vertices(f))))
+end
+function ket(f::AbstractFormNetwork)
+  return rename_vertices(inv_vertex_map(f), first(induced_subgraph(f, ket_vertices(f))))
+end
+function operator(f::AbstractFormNetwork)
+  return rename_vertices(
+    inv_vertex_map(f), first(induced_subgraph(f, operator_vertices(f)))
+  )
+end
+
+function derivative(f::AbstractFormNetwork, state_vertices::Vector; kwargs...)
+  tn_vertices = derivative_vertices(f, state_vertices)
+  return derivative(tensornetwork(f), tn_vertices; kwargs...)
+end
+
 function derivative_vertices(f::AbstractFormNetwork, state_vertices::Vector; kwargs...)
   return setdiff(
     vertices(f), vcat(bra_vertices(f, state_vertices), ket_vertices(f, state_vertices))
@@ -41,3 +60,4 @@ end
 operator_vertex_map(f::AbstractFormNetwork) = v -> (v, operator_vertex_suffix(f))
 bra_vertex_map(f::AbstractFormNetwork) = v -> (v, bra_vertex_suffix(f))
 ket_vertex_map(f::AbstractFormNetwork) = v -> (v, ket_vertex_suffix(f))
+inv_vertex_map(f::AbstractFormNetwork) = v -> first(v)
diff --git a/src/FormNetworks/bilinearformnetwork.jl b/src/FormNetworks/bilinearformnetwork.jl
index 5622fcb2..ecbbe01b 100644
--- a/src/FormNetworks/bilinearformnetwork.jl
+++ b/src/FormNetworks/bilinearformnetwork.jl
@@ -15,9 +15,9 @@ function BilinearFormNetwork(
   operator::AbstractITensorNetwork,
   bra::AbstractITensorNetwork,
   ket::AbstractITensorNetwork;
-  operator_vertex_suffix=default_operator_vertex_suffix,
-  bra_vertex_suffix=default_bra_vertex_suffix,
-  ket_vertex_suffix=default_ket_vertex_suffix,
+  operator_vertex_suffix=default_operator_vertex_suffix(),
+  bra_vertex_suffix=default_bra_vertex_suffix(),
+  ket_vertex_suffix=default_ket_vertex_suffix(),
 )
   tn = disjoint_union(
     operator_vertex_suffix => operator, bra_vertex_suffix => bra, ket_vertex_suffix => ket
diff --git a/test/test_forms.jl b/test/test_forms.jl
index aa533ebd..c391bd53 100644
--- a/test/test_forms.jl
+++ b/test/test_forms.jl
@@ -3,7 +3,15 @@ using Graphs
 using NamedGraphs
 using ITensorNetworks
 using ITensorNetworks:
-  delta_network, update, tensornetwork, bra_vertex_map, ket_vertex_map, dual_index_map
+  delta_network,
+  update,
+  tensornetwork,
+  bra_vertex_map,
+  ket_vertex_map,
+  dual_index_map,
+  bra,
+  ket,
+  operator
 using Test
 using Random
 
@@ -12,16 +20,20 @@ using Random
   s_ket = siteinds("S=1/2", g)
   s_bra = prime(s_ket; links=[])
   s_operator = union_all_inds(s_bra, s_ket)
-  χ = 2
+  χ, D = 2, 3
   Random.seed!(1234)
   ψket = randomITensorNetwork(s_ket; link_space=χ)
   ψbra = randomITensorNetwork(s_bra; link_space=χ)
-  A = delta_network(s_operator)
+  A = randomITensorNetwork(s_operator; link_space=D)
 
   blf = BilinearFormNetwork(A, ψbra, ψket)
   @test nv(blf) == nv(ψket) + nv(ψbra) + nv(A)
   @test isempty(externalinds(blf))
 
+  @test underlying_graph(ket(blf)) == underlying_graph(ψket)
+  @test underlying_graph(operator(blf)) == underlying_graph(A)
+  @test underlying_graph(bra(blf)) == underlying_graph(ψbra)
+
   qf = QuadraticFormNetwork(A, ψket)
   @test nv(qf) == 2 * nv(ψbra) + nv(A)
   @test isempty(externalinds(qf))
@@ -33,4 +45,7 @@ using Random
   @test tensornetwork(qf_updated)[bra_vertex_map(qf_updated)(v)] ≈
     dual_index_map(qf_updated)(dag(new_tensor))
   @test tensornetwork(qf_updated)[ket_vertex_map(qf_updated)(v)] ≈ new_tensor
+
+  @test underlying_graph(ket(qf)) == underlying_graph(ψket)
+  @test underlying_graph(operator(qf)) == underlying_graph(A)
 end