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Due to South Africa 's policy of Apartheid , Alex Metreveli and Istvan Guylas both refused to compete in the 1964 Wimbledon against Segal , a white South African .
 Alex Metreveli, Segal
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Alex Metreveli, Segal