Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{MAN_1959__138_160709, author = {F. HARARY}, title = {The {Number} of {Functional} {Digraphs.}}, journal = {Mathematische Annalen}, pages = {203--210}, publisher = {mathdoc}, volume = {138}, year = {1959}, zbl = {0087.38703}, url = {http://geodesic.mathdoc.fr/item/MAN_1959__138_160709/} }
F. HARARY. The Number of Functional Digraphs.. Mathematische Annalen, Tome 138 (1959), pp. 203-210. http://geodesic.mathdoc.fr/item/MAN_1959__138_160709/