On the number of descendants and ascendants in random search trees.
On the number of distributive lattices.
On the number of fully packed loop configurations with a fixed associated matching.
On the number of intervals in Tamari lattices. (Sur le nombre d'intervalles dans les treillis de Tamari.)
On the number of labeled -arch graphs.
On the number of matchings in regular graphs.
On the number of non-isomorphic Steiner triples
On the number of permutations admitting an th root.
On the number of possible row and column sums of -matrices.
On the permanents of certain circulant matrices and related Toeplitz matrices. (Über die Permanente gewisser zirkulanter Matrizen und damit zusammenhängender Toeplitz-Matrizen.)
On the powers of Motzkin paths.
On the q-log-Concavity of Gaussian Binomial Coefficients.
On the representation of abstract semigroups by transformation semigroups : Computer investigations.
On the sequence A079500 and its combinatorial interpretations.
On the system of all maximal chains (antichains) of a graph.
On the theory of Pfaffian orientations. I: Perfect matchings and permanents.
On the theory of Pfaffian orientations. II: -joins, -cuts, and duality of enumeration.
On the volume of a certain polytope.
On the volume of the polytope of doubly stochastic matrices.
On two combinatorial identities