I am trying to transfer some fields from accounts to contacts so I can better filter the contacts list. The issue is that this field is a multi-select field type, so I do not know what functions to use. So far my idea has been to do the below when creating a custom field using a formula:

CASE ( INCLUDE (Follow_Up__c, 'abc', 'bcd', 'cde'),
          'abc', 'abc',
          'bcd', 'bcd',
          'cde', 'cde',
          ' ' )
This does not work because the INCLUDE function will not accept multiple string literals. 

What would be the best way to change work with this multi-select picklist field to create a custom field in contacts using it?