Progress & Implementation in the 9YP, pt 4/2, 1971-72
From Peter Smith. 'The Universal House of Justice and the Baha’i World, 1963-1973'.
Main source: Messages from the Universal House of Justice, 1963-1986: The Third Epoch of the Formative Age.
https://www.amazon.com/Messages-Unive....
See also: Peter Smith and Moojan Momen. ‘The Baha’i faith, 1957-1988: a survey of contemporary developments’. Religion 19/1 (1989), pp. 63-91. DOI: 10.1016/0048-721X(89)90077-8.
Peter Smith. A Concise Encyclopedia of the Baha’i Faith. Oneworld, 2000.