too many individuals historically to name 'em all here, but top ones for sure in my "lifetime library" of experience would be following:
1.) my uncle Fred (took time to take me to conventions, meetings, gave me his coyote stretchers, fleshing beams, about 30 gallons of dry dirt, bait, lure, sifters, and just about every other trapping tool he owned when he decided to quit trapping. I've never forgotten any of his words or the use of all his stuff over the years. Fred was a coyote trapper primarily, but had trapped just about all of our species around here)
2.) Charlie Dobbins (Fred gave me a signed copy of his land trapping sets and techniques book. Fred met Charlie at a National convention when it was held here in Nebraska back in mid-late 70s. Its quite worn and tattered today but I still thumb through it prior to each season. Its my land set bible)
3.) Mr. Tom O's beaver articles in the Trapper and Predator caller have taken a lot of the guesswork out of beaver trapping for me, too. Up to this point, I've had more error than trial, it seems, but I have learned a lot on my own the hard way until I started seeing some of Tom's stuff and pictures.
4.) Bob Noonan on dryland coon trapping. I prefer land trapping to water trapping, and Mr. Noonan either mentioned some things in his articles that were new to me, or he reinforced what I thought I was experiencing, but either way I am able to hammer way more land set coon now than I ever did running water sets.
5.) Many, many individuals posting in this forum (Wacky, Rdfx, Asa, etc. etc. and the list really goes on and on here).
6.) Carol Black. Through his articles and books, I've picked up some tricks and techniques that have been very effective for me as well.
Jim-NE