basics / inexpensive but dated:

* Graph Theory And Its Applications by Jonathan Gross and Jay Yellen

* Introduction to Graph Theory by Richard J. Trudeau

comprehensive/expensive:

* Graph Theory And Its Applications by Jonathan Gross and Jay Yellen

* graph theory with computer systems emphasis: Applied Combinatorics by Alan Tucker

misc other sources:

* graph theory: https://diestel-graph-theory.com/

* Harris' Combinatorics and Graph Theory

* Graph Theory by Douglas B West

* combinatorial Optimization by Papadimitriou and Steiglitz