Jokes and Their Relation to the Unconscious is a 1905 book by Sigmund Freud that examines humor from the perspective of psychoanalysis and Freud's model of the human psyche (consisting of id, ego and superego). According to Freud, humor is the superego's allowing of unconscious and suppressed material to enter consciousness, producing pleasure through absurdity. Freud categorizes types of humor, differentiating between jokes and humor and tendentious and non-tendentious jokes.
This is a good choice if you're looking for a quick read or refresher rather than an in-depth analysis. You'll get a brief book summary and chapter by chapter breakdown. The website loads quickly with minimal advertising.