There is a book "Graph Theory" by Reinhard Diestel. There used to be an online version as a pdf, but it seems to be gone now. The Archive has it: http://web.arc

There is a book "Graph Theory" by Reinhard Diestel. There used to be an online version as a pdf, but it seems to be gone now. The Archive has it: http://web.archive.org/web/*/http://www.math.uni-hamburg.de/home/diestel/books/graph.theory/GraphTheoryIII.pdf http://web.archive.org/web/*/http://www.math.uni-hamburg.de/... (the pdf is almost 3 Mb).