diff --git a/src/models/append_graph.rs b/src/models/append_graph.rs
index 2423463..7868ae7 100644
--- a/src/models/append_graph.rs
+++ b/src/models/append_graph.rs
@@ -52,6 +52,8 @@ impl AppendGraph {
         }
     }
 
+    // Adds a single incidence of an edge, which is composed by two such incidences, to the
+    // incidences vector.
     fn add_incidence(&mut self, v1: Vertex, v2: Vertex) {
         self.incidences.push(IncidenceEntry {
             next: self.vertices[v1.0].first_incidence.take(),
diff --git a/src/models/graph.rs b/src/models/graph.rs
index 2ce0f8d..88e34a3 100644
--- a/src/models/graph.rs
+++ b/src/models/graph.rs
@@ -54,6 +54,8 @@ impl Graph {
         }
     }
 
+    // Adds a single incidence of an edge, which is composed by two such incidences, to the
+    // incidences arena, and returns its index.
     fn add_incidence(&mut self, v1: Vertex, v2: Vertex) -> Edge {
         let edge = self.incidences.insert(IncidenceEntry {
             next: self.vertices[v1].first_incidence.take(),