[1] H. Bielak:
On graphs with non-isomorphic 2-neighbourhoods. Čas. pěst. mat. 108 (1983), 294-298.
MR 0716415 |
Zbl 0526.05056
[3] F. Harary R. Z. Norman D. Cartwright:
Structural Models. An Introduction to the Theory of Directed Graphs. John Wiley Sons, INC. New York-London-Sydney, 1965.
MR 0184874
[4] J. Sedláček:
On local properties of finite graphs. Čas. pěst. mat. 106 (1981), 290-298.
MR 0629727