8493
This identification was made , in part , on the strength of reporting provided by Oleg Penkovsky , a double agent in the GRU working for CIA and MI6 .
 Oleg Penkovsky, GRU, CIA, MI6
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Oleg Penkovsky, GRU, CIA, MI6