300580
In the theoretical work of Karl Marx and Frederich Engels , socialization refers to the process of transforming an economic activity from a solitary activity to a social relationship .
 Karl Marx, Frederich Engels
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Karl Marx, Frederich Engels