Article: The 17 Designs That Bell Almost Used for the Layout of Telephone Buttons

The 17 Designs That Bell Almost Used for the Layout of Telephone Buttons

http://www.theatlantic.com/technology/archive/2013/08/the-17-designs-that-bell-almost-used-for-the-layout-of-telephone-buttons/279237/

Neat blast from the past and tangentially math related.