Letters - not many. He wasn't much of a letter writer and seems what he kept of drafts or letters received was by accident.

to Elsie Mitchell - 17 from 1964-1970, both originals and transcripts plus more on this card.

to Grahame Petchey - 6 from 1963-1971, just transcripts plus transcript of a letter from Kobun Chino to Grahame

Other Shunryu Suzuki letters and drafts and letters received