The effect op graph operations on the chromatic number (Papers/Books)

Can anyone please direct me to a paper or even a textbook which would provide a good read on how graph operations influence the chromatic number of a graph?

Thanks.

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Perhaps you could be more specific about what you mean by graph operations. It seems that there is a lot of them. – Martin Sleziak Sep 9 '12 at 9:13
Hi Martin, sorry I meant basic operations like the union (maximum chi of the 2 graphs, so that's simple), join, and products of graphs. Perhaps also the subdivision of a graph. – janvdl Sep 9 '12 at 10:31