You can always call Gleim or email them from their web page to ask if they have helicopter supplements. I've spoken to them that way and they've always been quite responsive. Plus I think they're the best study books.
I'm only fixed wing though so what do I know?
...just checked gleim.com. I guess you're sol there..
Outlines at the beginning of each chapter explaining concepts
Airplane only questions are included to save time and effort
Comprehensive Answer Explanations
Questions organized into logical topics