http://www.aapc.com home page of the American Academy of Professional Coders
https://www.ama-assn.org/practice-management/reporting-continued-issues-icd-10-claims ICD 10 overview by the American Medical Association.
http://www.aapc.com/ICD-10/codes/index.aspx translates from ICD-9 to ICD-10 or ICD-10 to ICD-9 ICD-10 The department of Health and Human Services (HHS) has mandated the replacement of the ICD-9-CM code sets medical coders and billers in the United States use now to report health care diagnoses and procedures with ICD-10 code sets, effective Oct. 1, 2013. ICD-10 implementation will radically change the way coding is currently done; the code-set will grow from its current 17,000 codes to more than 141,000, and the format is new with seven alpha-numeric codes instead of five numeric digits. These dramatic changes, and others, will require very significant effort to implement, and the time to prepare for ICD-10 implementation is now.
http://www.cms.gov/ICD9ProviderDiagnosticCodes/07_summarytables.asp New, Deleted, and Revised ICD-9-CM Codes – Summary Tables
https://www.federalregister.gov/ — Federal Register
http://www.cdc.gov/nchs/icd.htm use to download ICD-10-CM
http://www.icd9data.com/ Free ICD Codes – includes ICD 10 plus conversion tables.
https://www.aafp.org/fpm/toolBox/viewToolType.htm?toolTypeId=30 Family medicine codes from Family Practice Management and the American Academy of Family Physicians.
http://icd9cm.chrisendres.com/ includes a tabular index and an alphabetical index of diseases, procedures, the HCPCS alpha, plus others
https://en.wikipedia.org/wiki/ICD-10#List wikipedia can be edited by almost anyone; be wary of the information provided, double check in other resources; useful for finding additional keywords for a search and for the references/bibliography the articles provide.
http://www.findacode.com/ limited code information, can subscribe for more info
http://www.flashcode.com/ Use Free coding button on bottom left of screen – Limited trial offer