1. Excess cost of emergency department visits for nonurgent care;Baker;Health Affairs,1994
2. CDC 2013 Ambulatory health care data http://www.cdc.gov/nchs/ahcd.htm
3. Centers for Medicare and Medicaid Services 2013a Cost sharing out of pocket costs http://www.medicaid.gov/Medicaid-CHIP-Program-Information/By-Topics/Cost-Sharing/Cost-Sharing-Out-of-Pocket-Costs.html
4. Centers for Medicare and Medicaid Services 2013b Out-of-pocket cost exemptions http://www.medicaid.gov/Medicaid-CHIP-Program-Information/By-Topics/Cost-Sharing/Cost-Sharing-Exemptions.html
5. The effect of Medicaid premiums on enrollment: a regression discontinuity approach;Dague;Journal of Health Economics,2014