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The International Union of Crystallography has redefined the term " crystal " to include both ordinary periodic crystals and quasicrystals ( " any solid having an essentially discrete diffraction diagram " ) .
 International Union of Crystallography
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 International Union of Crystallography