ABOK is the reference... but most are better off using Tree Climbers Companion to learn which knots to tie. it's not important to know a large number of knots.
but it's very important to know the correct knots and how to tie those select knots well. the standard for climbers is can you tie the knot blindfolded. if the answer is no, more practice is needed.
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The Ashley Book of Knots is an encyclopedia of knots first published in 1944 by Clifford Warren Ashley. The culmination of over 11 years of work, it contains some 7000 illustrations and more than 3854 entries covering over 2000 different knots. The entries include instructions, uses, and for some knots, histories, and are categorized by type or usage. It remains one of the most important books on knots, as it is one of the most extensive, covering both good knots and bad, and noting which is which.