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

• Positron II
• Positron II
• Positron II
• Positron II

The image at the bottom-left-hand corner is labelled 'Positron II' but is might be better described as a Shimano Positron - without the 'II'.

So I think that the correct labels might be:

• Shimano Positron II
• Shimano Positron II
• Shimano Positron II
• Shimano Positron

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• Publisher: New Cycling
• Document: New Cycling May 1981 - Derailleur Collection
• Date: May 1981
• Derailleur brands: Shimano
• Derailleurs: Shimano Positron II, Shimano Positron II, Shimano Positron II, Shimano Positron (DG100 1st style)