ArithmometerLetters patent - Thomas de Colmar's Arithmometer
Burroughs Links
Burroughs Adding Machine Company - Glimpses into the Past
Burroughs Adding Machine Company (Michael Hancock)
Collections
Private Collection of Herman Price
Private Collection of Kees Nagtegaal
Comptometer Links
Comptometers - Biography of a machine by Brooke Boering
Curta Links
Facit Links
History of Facit Calculators by Christopher Noring
Odhner Links
Reference
Arithmometre.com (Valéry Monnier)
The Calculating Machines (DIE RECHENMASCHINEN) Ernst Martin
Contributions to the History of Mechanical Calculation Stephan Weiss
Original Documents on the History of Calculators
Patent database (from the great encyclopedia of mechanical calculating)
Mathematisches Maschinen-Museum
Ernie Jorgenson's Office Machine Americana
Vintage Calculators - (James Redin's X-Number World)
Recuerdos del Cálculo Mecánico
Typewriters
The Tyewriter Restoration Site
Chuck & Rich's Antique Typewriter website and museum
ETCetera (Early Typewriter Collectors)
Price-Less Antique Typewriters and Stuff
Typewriter Serial Number Database
The Antique Typewriter Down Under Connection
The Pace O'Shea Antique Typewriter Museum
Victor Links