273391
This classification was based on different studies dealing with the Clausiliidae , published by H. Nordsieck in 1978 , 1979 , 1981 , 1985 , 1994 , 1997 and 1998 .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 None