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2. Incidence and nature of tumors in captive wild mammals and birds;Ratcliffe;Am J Cancer,1933
3. Frequency and types of tumors in mammals and birds of the Philadelphia Zoological Garden;Lombard;Cancer Res,1959
4. Neoplasia in zoo animals;Hubbard;J Zoo An Med,1983
5. Observations on naturally occurring neoplasms in birds in the state of Victoria, Australia;Reece;Avian Pathol,1992