PPOs: a challenge to HMOs?
D004465:Economic Competition / Q000331:legislation & jurisprudence*; D004467:Economics / Q000331:legislation & jurisprudence*; D005161:Facility Regulation and Control / Q000331:legislation & jurisprudence; D006279:Health Maintenance Organizations / Q000331:legislation & jurisprudence*; D007348:Insurance, Health / Q000331:legislation & jurisprudence*; D011243:Preferred Provider Organizations / Q000331:legislation & jurisprudence*; D014481:United States