Signed 2-independence in digraphs
Discrete Mathematics 312 (2012), no. 2, 465-471.
BibTex references
@Article\{Vol12,
author = "Volkmann, Lutz",
title = "Signed 2-independence in digraphs",
journal = "Discrete Mathematics",
number = "2",
volume = "312",
pages = "465-471",
year = "2012",
note = "http://dx.doi.org/10.1016/j.disc.2011.09.009",
}