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Most attention has been paid to the Healthy Women Study ( HWS ) , Study of Women ' s Health across the Nation ( SWAN ) , the Nurses ' Health Study ( NHS ) , and the Rancho Bernardo Study ( RBS ) because they continue to produce recent publications designed to distinguish the effect of age from the effect of menopause .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None