Dec. 1970 issue called introductory issue; numbering begins with: Vol. 1, no. 2 (Feb./Mar. 1971).
Some numbers issued in combined form.
Issue for Dec. 1996/Jan. 1997 called volume 24, no. 12 but constitutes volume 24, no. 12 and volume 25, no. 1 combined.
Not published July 1997 and March 2001.
Issue for June/Jully 2003 called volume 31, no. 4 but constitutes volume 31, no. 3.
Month designations dropped beginning in 2004.