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After the discovery of the hydrogen bonded A : T and C : G pairs , Watson and Crick soon had their anti-parallel , double helical model of DNA , with the hydrogen bonds at the core of the helix providing a way to " unzip " the two complementary strands for easy replication : the last key requirement for a likely model of the genetic molecule .
 Watson, Crick
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Watson, Crick