1. Representation of Switching Circuits by Binary - Decision Programs;Lee;BSTJ,1959
2. The Synthesis of Two-Terminal Switching Circuits;Shannon;BSTJ,1949
3. Sequential Controllers used for Industrial Automation;Webb,1974
4. The Problem with Programmable Controllers;Smith;IEEE Transactions IECL,1974
5. Bulletin 1750 PMC Programmable Controller,1972