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Human Rights Watch has called on both warring factions to cease using the unguided BM-21 Grad missiles in populated areas , and has said the use of these weapons systems was a violation of international humanitarian laws and could constitute a war crime .
 Human Rights Watch
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:
 Human Rights Watch