This installment was originally published in Look and Learn issue no. 651 on 6 July 1974.
The Prisoner of Zerss (continued . . .)
This installment was originally published in Look and Learn issue no. 522 on 15 January 1972.
The Duplication Machine (continued . . .)
This installment was originally published in Look and Learn issue no. 504 on 11 September 1971.
