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These include author Robert A. Heinlein naming a character after him in his 1940 short story " Blowups Happen " , and science fiction writer A. E. van Vogt in his novel " The World of Null-A " , published in 1948 .
 person: Robert A. Heinlein; person: A. E. van Vogt
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Robert A. Heinlein, A. E. van Vogt 
Answer:
 person: Robert A. Heinlein; person: A. E. van Vogt