“Nixon will be remembered as a classic case of a smart man shitting in his own nest. But he also shit in our nests, and that was the crime that history will burn on his memory like a brand. By disgracing and degrading the Presidency of the United States, by fleeing the White House like a diseased cur, Richard Nixon broke the heart of the American Dream.”

Brown : The Last Discovery of America (2003)

1990s, He Was A Crook (1994)

In Bitter American Exile, the Shah's Twin Sister, Ashraf, Defends Their Dynasty (1980)

On the legacy of then-American president Richard Nixon and his successors, pg. 217
The Woman I Am: A Memoir (2006)

Though at times attributed to Leary on the internet, no published source of this has been located. It is a misquote of a William S. Burroughs reading entitled M.O.B. from the Giorno Poetry Systems boxed set. M.O.B. was an extension of Burroughs' expression in The Place of Dead Roads (1983), p. 155:
You are a Shit Spotter. It's satisfying work. … We have observed that most of the trouble in the world has been caused by ten to twenty percent of folks who can't mind their own business, because they have no business of their own to mind, any more than a smallpox virus … The mark of a basic shit is that he has to be right.
Misattributed

In a Stanley Siegel interview (c. 1977) http://www.youtube.com/watch?v=3HrdNRvJ7-8, with phone commentary by Art Linkletter who blamed his daughter's death on her involvement with LSD.

Part II, chapter 5.
Proverbs (1546), Bartlett's Familiar Quotations, 10th ed. (1919)

To My People (July 4, 1973)

He smiled and replied “You have a point there!”.
During the official visit of President Richard Nixon to India, quoted In: P.250.
Law in the Scientific Era