8 books
An Easy Course in Programming the Hp48 G/Gx
An Easy Course in Using the HP-17bii
The Answers You Need for the Hp95lx Palmtop
An Easy Course in Using the HP 19bii
An Easy Course in Using the HP-42s
An Easy Course in Using the HP-12c & Other HP Financial Calculators
An Easy Course in Using the HP-12c
An Easy Course in Programming the HP-41