1. Beer, Stafford, “Below the Twilight Arch: A Mythology of Systems”; chap. 1, Systems Research and Design (John Wiley, 1961).
2. Beer, Stafford, The Cost Accountant, 42, No. 6, June 1964 (also obtainable from SIGMA, Ltd., as a pamphlet).
3. Ross Ashby, W., Design for a Brain (Chapman and Hall (London), 1952: revised edition, 1960).
4. Beer, Stafford, Operational Res. Quart., 13, No. 2 (June 1962).
5. Beer, Stafford, The Manager, October and November, 1963; Metra Journal, 3, No. 1 (1964) (also obtainable from SIGMA, Ltd., as a reprint).