1. Agency for Healthcare Research and Quality (AHRQ) 2009a Clinical Classifications Software (CCS) for ICD-9-CM http://www.hcup-us.ahrq.gov/toolssoftware/ccs/ccs.jsp
2. Agency for Healthcare Research and Quality (AHRQ) 2009b MEPS HC-110F Codebook 2007 Outpatient Department Visits http://www.meps.ahrq.gov/mepsweb/data_stats/download_data/pufs/h110f/h110fcb.pdf
3. Agency for Healthcare Research and Quality (AHRQ) 2009c MEPS HC-110G Codebook 2007 Office-based Medical Provider Visits http://www.meps.ahrq.gov/mepsweb/data_stats/download_data/pufs/h110g/h110gcb.pdf
4. American Physical Therapy Association 2004 Position on Principles and Objectives for the United States Health Care System and the Delivery of Physical Therapy Services HOD P06-04-17-16 http://www.apta.org/uploadedFiles/APTAorg/About_Us/Policies/HOD/Health/Principles.pdf
5. American Physical Therapy Association 2011 A Summary of Direct Access Language in State Physical Therapy Practice Acts: Direct Access to Physical Therapy Laws http://www.apta.org/uploadedFiles/APTAorg/Advocacy/State/Issues/Direct_Access/DirectAccessbyState.pdf