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QOOP also provided on-demand publishing services , and had partnered with publishers such as CK-12 Foundation , Stanford University Press , and PLoS ( Public Library of Science ) to provide printing of textbooks and compendiums .
 CK-12 Foundation, Stanford University Press, PLoS
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 CK-12 Foundation, Stanford University Press, PLoS