48422
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 .
 Robert A. Heinlein, Blowups Happen, A. E. van Vogt, The World of Null-A
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Robert A. Heinlein, Blowups Happen, A. E. van Vogt, The World of Null-A