52443
According to Steven H Silver , an American science fiction editor , alternate history requires three things : a point of divergence from the history of our world prior to the time at which the author is writing , a change that would alter history as it is known , and an examination of the ramifications of that change .
 Steven H Silver
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Steven H Silver