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In their work dr Gontarczyk and dr Cenckiewicz give proof that in the 1970s the NSZZ Solidarność leader and former President of Poland Lech Wałęsa was a secret informant of the Polish communist secret police - Służba Bezpieczeństwa ( SB ) .
 Gontarczyk, Cenckiewicz, NSZZ Solidarność, Poland Lech Wałęsa, Polish communist, Służba Bezpieczeństwa
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Gontarczyk, Cenckiewicz, NSZZ Solidarność, Poland Lech Wałęsa, Polish communist, Służba Bezpieczeństwa