diff --git a/polymani.pl b/polymani.pl
index 858bb24..6a78207 100644
--- a/polymani.pl
+++ b/polymani.pl
@@ -641,6 +641,18 @@ list_to_polynomial([T], T).
 %% Tests:
 %% ?- list_to_polynomial([1, x, x^2], P).
 %@ P = x^2+x+1.
+%% ?- list_to_polynomial([-1, -x, -x^2], P).
+%@ P = -x^2-x-1.
+%% ?- list_to_polynomial([1, -x, x^2], P).
+%@ P = x^2-x+1.
+%% ?- list_to_polynomial([x^2, x, 1], P).
+%@ P = 1+x+x^2.
+%% ?- list_to_polynomial([a,-e], P).
+%@ P = -e+a.
+%% ?- list_to_polynomial([], P).
+%@ false.
+%% ?- list_to_polynomial([a], P).
+%@ P = a.
 
 %% negate_term(T, T2) is det
 %
@@ -696,6 +708,8 @@ scale_polynomial(P, C, S) :-
 %  Add an atom C to the head of a list L.
 %
 cons(C, L, [C | L]).
+%% Tests:
+%% It just trivially works.
 
 %% add_polynomial(+P1:polynomial,+P2:polynomial,-S:polynomial) is det
 %