Open J. Discrete Math. Vol.9 No.3, July 26, 2019 DOI:10.4236/ojdm.2019.93008
Open J. Discrete Math. Vol.9 No.3, July 09, 2019 DOI:10.4236/ojdm.2019.93007
Open J. Discrete Math. [ISSUE], [PUBDATE] DOI:[DOI]