Randall, David (May 1991). "Focus"(PDF). Record Collector (141): 102–107. Archived from the original(PDF) on 20 June 2021. Retrieved 21 January 2017.[failed verification]
Randall, David (May 1991). "Focus"(PDF). Record Collector (141): 102–107. Archived from the original(PDF) on 20 June 2021. Retrieved 21 January 2017.[failed verification]