- Official ICD-9-CM Guidelines
http://www.cdc.gov/nchs/icd.htm
- Medicare Learning Network- Many free educational materials from CMS
http://www.cms.hhs.gov/MLNGenInfo/
- American Academy of Professional Coders
http://www.cdc.gov/nchs/icd.htm
http://www.cms.hhs.gov/MLNGenInfo/