It’s worth having a hardcopy version of Ashley’s Book Of Knots if you’re really into this sort of thing... but for (my) practical purposes, i prefer John Long’s “Climbing Anchors”.
Long's books are definitive in the world of climbing, but the knots he teaches are limited by the needs of climbers. He isn't big on slip knots or knots that require tension (sheepshank) because those aren't safe for climbing. Knots for lashing and knots designed for natural fiber rope are similarly absent. Many a climber thinks they know knots until asked to lash a pair of ladders together.
Ironically the most common knot in all climbing, the one used by virtually every climber every day, isn't in Long's books. He doesn't teach how to lace and tie your climbing shoes. There are right and wrong ways. I have seen a climber injured by incorrectly tied boots. They hurt their foot and couldn't remove the boot quickly because the laces were all wrong.
https://itunes.apple.com/us/app/animated-knots-by-grog/id376...
https://play.google.com/store/apps/details?id=com.animatedkn...
It’s worth having a hardcopy version of Ashley’s Book Of Knots if you’re really into this sort of thing... but for (my) practical purposes, i prefer John Long’s “Climbing Anchors”.