Please excuse the awful pun in the subject line, but summer vacation time added to travel restrictions may mean you will have a lot more time to study up on the kinds of topics you need to master to get better at your chosen profession.
The Science and Technology of Dog Training 2nd edition or Problem Animal Behavior by James O'Heare.
So whether you have more down time at home or (if you are lucky) in a vacation home or even an RV, here are some relatively challenging books you should consider:
Any of the Behaviorology books by Stephen Ledoux, now reduced in price!
Behavior Adjustment Training 2.0 by Grisha Stewart.
The Domestic Dog 2nd edition edited by James Serpell.
Dog Behavior - Modern Science and Our Canine Companions by James Ha and Tracy Campion.
Any of the Dog Trainer Resource books from APDT's Canine Chronicle
And if you just want to relax with a fun mystery, try A Borrowing of Bones by Paula Munster.