Hewlett Packard
HP-70
HP calculators - Wikipedia
The Evolution and History of HP Calculator - YouTube
Hewlett-Packard Calculator Archives - HP History
File:Vintage Hewlett-Packard Model HP-45 Advanced Scientific Pocket Calculator, HP's Third Handheld Electronic Calculator, Introduced in 1973 and Discontinued in 1976 (11590594223).jpg - Wikimedia Commons
The Hewlett Packard Calculator Page
HP calculators - Wikipedia
HP Calculators History
Hewlett-Packard Calculator Archives - HP History
Hewlett-Packard Calculator Archives - HP History
Hewlett-Packard HP-28C Handheld Electronic Calculator | National Museum of American History
HP 48 series - Wikipedia
HP Computer Museum
HP-80 History, Design and Interesting Facts
HP-35 - Wikipedia
Hewlett-Packard Calculator Archives - HP History
HP Series E Calculators - Hewlett-Packard History
The Hewlett Packard Calculator Page
The HP-35
HP-67/97
The Calculators Brief History: When was the calculator invented
