Principles of combinatorics, Volume 72 (Mathematics in Science and Engineering) by Berge
Publisher: Academic Press (February 11, 1971) | ISBN: 0120897504 | Pages: 176 | PDF | 2 MB

Most mathematicians of this day, confronted with an argument requiring combinatorial thinking, react with one of two stock phrases: (a) "This is a purely combinatorial argument," (b) "This is a difficult combinatorial argument." Hypnotic repetition of either of these slogans is likely to have the same balming effect on the speaker: freed from all scruples, he will pass the buck and unload the work onto someone else's shoulders.