Coba jelasin Lihat pula dari Mesin tik dong

David, P.A. 1986. Understanding the Economics of QWERTY: The Necessity of History. In: Parker, William N.: Economic History and the Modern Economist. Basil Blackwell, New York and Oxford.

Thompson, Holland. The Age of Invention: A Chronicle of Mechanical Conquest. 2009. BiblioBazaar, LCC.