The first author one should encounter relative to bumble bees, in my humble opinion, is Dave Goulson.
He is both a world renowned bumble bee ecologist and a very engaging popular writer.
bumblebee behavior, ecology and conservation, Dr Dave Goulson, 2010
He has a series of great reads on bees and other insects including:
A Sting in the Tail,
A Buzz in the Meadows, and
The expanding Pacific Northwest range of Bombus impatiens Cresson and its establishment in Washington state Chris Looney, James P. Strange, Maggie Freeman & David Jennings, Biological Invasions Vol 21 #6, June 2019 ISSN 1387-3547