A Logical Introduction to Proof

From the reviews:

“Cunningham (Buffalo State, SUNY) focuses on the strategies for different proof techniques. … The well-written text is consistent in its focus, which should help students. The book includes sufficient, appropriate exercises. … contains ample notes to guide students through most of the exercises. Whether used for a course or as a reference for students learning proof techniques, this book is certainly worthy of consideration. Summing Up: Highly recommended. Lower-division undergraduates through graduate students.” (J. R. Burke, Choice, Vol. 51 (1), September, 2013)