APA
Abraham J., . (1999). Enter at your own risk : HMO participation and enrollment in the medicare risk market. Cambridge, Mass: National Bureau of Economic Research.
Chicago
Abraham Jean, . 1999. Enter at your own risk : HMO participation and enrollment in the medicare risk market. Cambridge, Mass: National Bureau of Economic Research.
Harvard
Abraham J., . (1999). Enter at your own risk : HMO participation and enrollment in the medicare risk market. Cambridge, Mass: National Bureau of Economic Research.
MLA
Abraham Jean, . Enter at your own risk : HMO participation and enrollment in the medicare risk market. Cambridge, Mass: National Bureau of Economic Research. 1999.