Outside activities ethics guideline documents:

A Word About Ethics (FAQs)    
Appearances of Bias
Contacting the Federal Government
Disqualification and Recusal
Misuse of Government Resources
Non-Federal Employment and Activities
Service with Non-Federal Entities
Outside Writing
Ethics At A Glance (Graphical Depictions)    
Appearances of Bias
Disqualification and Recusal
Non-Federal Employment and Activities
Service with Non-Federal Entities
Other Guidance
Guidelines for Service with an Outside Organization in an Official Capacity
Social Media
3 Minutes of Ethics - Outside Activities