@article{Skowronek-Kaziów:2009,
author
=
"J.Skowronek-Kaziów",
title
=
"Properties of digraphs connected with some congurence relations",
journal
=
"Czechoslovak Mathematical Journal",
volume
=
"Vol. 59",
number
=
"no 1",
pages
=
"39--49",
year
=
"2009",
}