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The term " neutronium " was coined in 1926 by Andreas von Antropoff for a conjectured form of matter made up of neutrons with no protons or electrons , which he placed as the chemical element of atomic number zero at the head of his new version of the periodic table .
 Andreas von Antropoff
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Andreas von Antropoff