- Michel Las Vergnas:
Acyclic and totally cyclic orientations of combinatorial geometries. Discret. Math. 20: 51-61 (1977) - Philippe Vincke:
Quasi-kernels of minimum weakness in a graph. Discret. Math. 20: 187-192 (1977) - Mieczyslaw Wojtas:
On seven mutually orthogonal Latin squares. Discret. Math. 20: 193-201 (1977)
