March 1991 Vol. 10, No. 1 & 2 16 2,707k March 1991 Vol. 10, No. 3 & 4 16 2,454k March 1991 Vol. 10, No. 5 & 6 16 2,402k March 1991 Vol. 10, No. 7 8 1,412k March 1991 Vol. 10, No. 8 & 9 16 2,728k March 1991 Vol. 10, No. 9 & 10 16 2,446k March 1991 Vol. 10, No. 11 & 12 16 2,447k April 1991 Vol. 10, No. 13 15 1,842