diff --git a/doc/min_cost_flow.dox b/doc/min_cost_flow.dox
--- a/doc/min_cost_flow.dox
+++ b/doc/min_cost_flow.dox
@@ -26,7 +26,7 @@
 The \e minimum \e cost \e flow \e problem is to find a feasible flow of
 minimum total cost from a set of supply nodes to a set of demand nodes
 in a network with capacity constraints (lower and upper bounds)
-and arc costs.
+and arc costs \ref amo93networkflows.
 
 Formally, let \f$G=(V,A)\f$ be a digraph, \f$lower: A\rightarrow\mathbf{R}\f$,
 \f$upper: A\rightarrow\mathbf{R}\cup\{+\infty\}\f$ denote the lower and
@@ -78,7 +78,7 @@
    - if \f$lower(uv)<f(uv)<upper(uv)\f$, then \f$cost^\pi(uv)=0\f$;
    - if \f$cost^\pi(uv)<0\f$, then \f$f(uv)=upper(uv)\f$.
  - For all \f$u\in V\f$ nodes:
-   - \f$\pi(u)<=0\f$;
+   - \f$\pi(u)\leq 0\f$;
    - if \f$\sum_{uv\in A} f(uv) - \sum_{vu\in A} f(vu) \neq sup(u)\f$,
      then \f$\pi(u)=0\f$.
  
@@ -145,7 +145,7 @@
    - if \f$lower(uv)<f(uv)<upper(uv)\f$, then \f$cost^\pi(uv)=0\f$;
    - if \f$cost^\pi(uv)<0\f$, then \f$f(uv)=upper(uv)\f$.
  - For all \f$u\in V\f$ nodes:
-   - \f$\pi(u)>=0\f$;
+   - \f$\pi(u)\geq 0\f$;
    - if \f$\sum_{uv\in A} f(uv) - \sum_{vu\in A} f(vu) \neq sup(u)\f$,
      then \f$\pi(u)=0\f$.