Federal Reserve Bank of Minneapolis Community Development Project. "Consumer Price Index (estimate) 1800–" (英語). Federal Reserve Bank of Minneapolis. 2019年1月2日閲覧。
nasa.gov
jsc.nasa.gov
Whittle, David W (Feb 16, 2006). “NASA Space Center” (PDF). Oral History Project. 2016年6月11日閲覧。
old-computers.com
“Olivetti Programma P101/P102”. Old Computers. 2016年6月11日閲覧。 “The P101, and particularly the magnetic card, was covered by a US patent (3,495,222, Perotto et al.) and this gave to Olivetti over $900.000 in royalties by HP alone, for the re-use of this technology in the HP9100 series.”
