224391
Nikolay P. Serdev , M.D. , Ph.D. , ( b. April 26 , 1948 ) is a Sofia , Bulgaria based board certified specialist in General Surgery and Cosmetic Surgery .
 Nikolay P. Serdev, Sofia
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Nikolay P. Serdev, Sofia