Note
QST, Jan 1965, p. 137.
QST, Feb 1965, p. 158.
QST, Jun 1965, p. 125.
CQ, Jun 1965, p. 54. (some small explanation)
QST, May 1966, p. 153.
QST, Jan 1967, p. 141.
QST, Jan 1968, p. 145.
References
Brief description. Electronics World, Mar 1965, p. 92.