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In 1990 , Styx ( minus Tommy Shaw , who was replaced by guitarist / singer-songwriter Glen Burtnik ) returned to the studio for the album " Edge of the Century " ( 1990 ) .
 Styx, Tommy Shaw, Glen Burtnik
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Styx, Tommy Shaw, Glen Burtnik