These classics about controlled intercourse are available here. You can read them online by following the links, or, in some cases, download and print them out:
The Karezza Method (entire text) by J. William Lloyd (1931)*
This book, written by a man, is a beautiful, inspiring manual about the practice of Karezza. It's full of practical information and highly recommended. Choose from PDF e-book, Epub version, Mobi version, PDF version reduced to minimum pages for printing or scan of original book.
Karezza: Ethics of Marriage (entire text) by Alice Bunker Stockham, MD (1903)*
Stockham was a Quaker and one of the first women graduated from medical school in the USA. Her book is less user-friendly than Lloyd's, but also very inspiring. She spends a lot of effort on the larger spiritual implications of the practice. The letters from those practicing Karezza, found near the back, are particularly valuable.
Choose from original 1896 edition: PDF e-book version, Epub version, Mobi version, or revised 1903 edition: PDF e-book version, Epub version, Mobi version and scan of actual 1903 book or version that is reduced to 26 printable pages. And here's a comparison of the two versions.
Male Continence (entire text) by John Humphrey Noyes (1872)*
This is a pamphlet that Noyes prepared after 25 years of experience among an entire community with the practice he called "male continence." He stumbled upon the practice himself, after vowing not to put his wife through another agonizing pregnancy. He includes practical tips. (PDF version and PDF of original text)
Sex Perfection and Marital Happiness (excerpts) by Rudolf von Urban, MD (1949)
Von Urban was a Freudian psychiatrist who counseled couples who were planning to divorce. Often he was able to help them save their marriages with his "six rules for human sex relations." The chapters included here address the separation problem between the genders, the bio-energetic aspects of sex, and masturbation. He also furnishes many case studies of couples in trouble who experimented with his advice. Very practical. View scan of entire book.
Essay on karezza's heritage by Aldous Huxley
Essay about the larger ramifications of the practice of sex without orgasm.
Love, Sex & Nutrition (excerpts) by Bernard Jensen, ND PhD
Short excerpt from Dr. Jensen's book, in which he describes the benefits of Karezza.
Review of book by Dr. S.S. Bass. He practices a version of karezza that is really more "Male Continence."
The Better Way by A.E. Newton (1875)
These few pages are scans from an old book that advises continence except when procreation is desired.
Truth About Sex by Paul C. Bragg (1929)
This book has a few pages on transmutation of sexual energy via continence.
Website with articles and essays about karezza from various places. *As best we can tell the copyrights of these works have expired, so they are free for everyone.