Remember that popups can be a distracting to limit their frequency below.
Rotary Wing Flight ISBN 978-1-56027-118-5 #ASA-RW-4
Reprint of U.S. Army FM 1-51, edited and adapted for civilian helicopter students.
Includes discussion on helicopter aerodynamics, common flight techniques, normal field operations, precautionary measures, and critical conditions.
Rotary Wing Flight by U.S. Army ISBN 978-1-56027-118-5 ASA-RW-4