Have you checked out the educational video subscription through this website? https://www.ideafit.com/fitness-videos There are tons of videos with tips and training in them. We also have our online publications you might want to check out IDEA Trainer Success and IDEA Fitness Manager
I think it is important for fitness professionals to have great library to refer to when they have questions related to exercise science and physiology.
With that said I would suggest ACSM Guideline to Exercise Testing and Prescription in addition to NSCA Essentials to Strength and Conditioning.
In an ideal situation, I would also suggest taking out membership with both organizations so that you you receive their research journals on a monthly basis.