Male orgasm and ejaculation are not synonymous with each other. Orgasm can occur without ejaculation, and ejaculation can occur without orgasm. They are two separate physiological processes. In the former it is referred to as a male orgasm (the non-ejaculatory variety, a.k.a. coitus reservatus, Tantric, Taoist: depending on your sexosophy), in the latter it is known as ejaculatory anhedonia, which is referred to in the literature as being a medical condition.
I have read the following book. I highly recommend it for learning the technique. It is heavy on the sexosophy of eastern philosophy. If the sexosophy is not your cup of tea, just skip to the exercises
Some men choose to use a variety of different techniques which enable them to have multiple orgasms without ejaculation. Here I will list the various different techniques by their scientific terms. All of the following have been used in history as a natural male form of birth control. If the origin is known I will list.
Coitus prolongatus - which is a form of prolonged sexual intercourse with minimal thrusting and without ejaculation.
Karezza - same definition as above. Originated in ancient Persia, traveled via India throughout the rest of the Orient. Utilizes breathing control, meditation, and finger pressure to avert ejaculation. Similar to Tantric and Taoist approach.
Coitus reservatus - originated in the Orient: Tantric and Taoist approach. Also known as Maithuna or coitus prolongatus. Was used by Oneida Community in United States during the 19th century as a form of birth control. John Noyes, the founder of the community, published Male Continence which described the technique as well as the sexosophy of this method.
Coitus saxonicus - originated with the Germanic Saxons after they invaded England in the fifth century. It utilizes a finger squeeze technique which puts pressure on the urethra at the base of the penis (along the perineum on the corpus cavernosum).
Retrograde ejaculation - which can be induced utilizing finger or muscle squeeze techniques. sometimes in the medical literature is referred to as a condition if it is not induced (i.e. occurs without intention).
The various stages of sexual arousal were measured by Masters and Johnson following the pioneering research of Kinsey. Masters and Johnson studied the anatomy and physiology of human sexual response using direct observation between 1957 in 1965 and published it in their book Human Sexual Response. Masters and Johnson categorized the human sexual response cycle as follows: excitement phase, plateau phase, orgasmic phase,and resolution phase (aka refractory period).
Orgasm research which is currently being undertaken by Beverly Whipple et al, reveals that the human sexual response cycle may not be quite as simple as Masters and Johnson categorized it. Here is their book Science of Orgasm. Male multiple orgasm, has been found to have no refractory period, therefore, no post-intercourse fatigue. A non-technical book discussing this method is Multi-Orgasmic Man. Another form of orgasm which is currently being researched is that of the mental orgasm. For details see http://barbaracarrellas.com/
I am still doing independent research in this subject. I will post additional information as I find more data.