Willemsen, R. E. (?????.).  (1987).  Possible presence of Testudo graeca ibera on the Peloponnesos, Greece.. LacertaLacerta, 45, 169-171.

Willemsen, R. E. (?????.).  (1991).  Differences in thermoregulation between Testudo hermanii and Testudo marginata and their ecological significance.. Herpetological JournalHerpetological Journal, 1, 559-567.

Willemsen, R. E., & Hailey, A. (?????.).  (1989).  Status and conservation of tortoises in Greece. Herpetological JournalHerpetological Journal, 1, 315-330.

Willemsen, R. E., & Hailey, A. (?????.).  (2001).  Effects of spraying the herbicides 2, 4-D and 2, 4, 5-T on a population of the tortoise Testudo hermanni in southern Greece. Environmental PollutionEnvironmental Pollution, 113, 71-8.

Hailey, A., & Willemsen, R. E. (?????.).  (2003).  Changes in the status of tortoise populations in Greece 1984?2001. Biodiversity and ConservationBiodiversity and Conservation, 12, 991-1011.