My rough translations of the photo captions, clockwise from top left are:

• F-I
• PF
• PA
• F-II

• Publisher: New Cycling
• Document: New Cycling May 1981 - '81 Derailleur Collection
• Date: May 1981
• Derailleur brands: Sanko
• Derailleurs: Sanko F1, Sanko F2, Sanko PA, Sanko PF