Answer by taking a quote from the following article:

Randi was born on August 7, 1928 in Toronto, Ontario, Canada, the son of Marie Alice (nee Paradis) and George Randall Zwinge. He has a younger brother and sister. He took up magic after seeing Harry Blackstone Sr. and reading conjuring books while spending 13 months in a body cast following a bicycle accident. He confounded doctors who expected he would never walk again.

Randi is the author of ten books, among them Conjuring (1992), a biographical history of noted magicians. The book is subtitled Being a Definitive History of the Venerable Arts of Sorcery, Prestidigitation, Wizardry, Deception, & Chicanery and of the Mountebanks & Scoundrels Who have Perpetrated these Subterfuges on a Bewildered Public, in short, MAGIC! The book's cover says that it is by "James Randi, Esq., A Contrite Rascal Once Dedicated to these Wicked Practices but Now Almost Totally Reformed". The book selects the most influential magicians and tells some of their history, often in the context of strange deaths and careers on the road. This work expanded on Randi's second book titled Houdini, His Life and Art. This illustrated work was published in 1976 and was co-authored with Bert Sugar. It focuses on the professional and private life of Houdini.  Randi also wrote a children's book in 1989 titled The Magic World of the Amazing Randi, which introduced children to magic tricks. In addition to his magic books, he has written several educational works about paranormal and pseudoscientific claims. These include biographies of Uri Geller and Nostradamus as well as reference material on other major paranormal figures. He is currently working on A Magician in the Laboratory, which recounts his application of skepticism to science. He was a member of the all-male literary banqueting club the Trap Door Spiders, which served as the basis of his good friend Isaac Asimov's fictional group of mystery solvers, the Black Widowers.  Other books are Flim-Flam! (1982), The Faith Healers (1987), James Randi, Psychic Investigator (1991), Test Your ESP Potential (1982) and An Encyclopedia of Claims, Frauds, and Hoaxes of the Occult and Supernatural (1995).  Randi was a regular contributor to Skeptic magazine, penning the "'Twas Brillig..." column, and also served on its editorial board. He is also a frequent contributor to Skeptical Inquirer magazine, which is published by CSI, of which he is also a Fellow.

Did anyone else help his with these books?