Someone I was mentoring had trouble with maths formulas so he photoread some books that taught the basic (level lower than what he was working with) he found that afterwards the answers started flowing.
It is definately a good idea to photoread other books on the same subjects. Especially if the core book is giving you trouble. You might find that another author has explained it in a manner that you can understand it better. So photoread the books and activate the one or two you feel drawn to activate... along with the core book. Most of the other books you will only need to photoread with little activation. Just be sure you follow your instinct/intuition and read the passages that catch your interest since it's quite possible that you 'understand' the concepts from those books to carry over to activating your core books.
Alex
