Very good suggestion. Here's is a similar but free book: http://people.uleth.ca/~dave.morris/books/proofs+concepts.html http://people.uleth.ca/~dave.morris/book

Very good suggestion. Here's is a similar but free book: http://people.uleth.ca/~dave.morris/books/proofs+concepts.html http://people.uleth.ca/~dave.morris/books/proofs+concepts.ht...