Is Barron's Incomplete?

[ai434]

Hello everyone, wish I had found this forum at the start of the summer when I started studying for the gre, which i am taking at the end of this month.


I've been using Barron's all summer and have memorized all the info in the math section. However, I picked up a Princeton Review for the hell of it and found that they discussed permutions AND combinations, while barron's apparently only deals with the former. I can't believe that Barron's, which goes over every little detail in every subject, skipped over this, while Princeton, which has very little depth, has. What worries me is what else is this book is lacking. Does anyone have any recommendations? I am most obliged for any insight.