20676
" Many people have also spoken of the shocking news , compounded by the pall of uncertainty about the identity of the assassin ( s ) , the possible instigators , and the causes of the killing , as an end to innocence , and in retrospect it has been coalesced with other changes of the tumultuous decade of the 1960 s , especially the Vietnam War .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 None