The photo captions, clockwise from top left are:

• 2000
• 2000
• 2000
• 2000

I think that more accurate labels might be:

• Zeus 2000
• Zeus Criterium
• Zeus 2000 (but its a front derailleur)
• Zeus 2000

• Publisher: New Cycling
• Document: New Cycling May 1981 - '81 Derailleur Collection
• Date: May 1981
• Derailleur brands: Zeus
• Derailleurs: Zeus 2000, Zeus 2000, Zeus Criterium