求助如下卫生经济学文献

各位同学，本人索求如下卫生经济学相关的文献：

• Enthoven, A. (1978), "Consumer choice health plan", New England Journal of Medicine 298(12):650-658.

• Ma, A. (1994), "Health care payment systems: Cost and quality incentives", Journal of Economics and Management Strategy 3(1):93-112.

• Melnick, G., et al. (1992), "The effects of market structure and bargaining position on hospital prices", Journal of Health Economics 11(3):217-233.

• Scheffler, R., S. Sullivan and T. Ho (1991), "The impact of Blue Cross and Blue Shield utilization management programs: 1980-1988", Inquiry 28:263-275.

• Pope, G.C. (1989), "Hospital nonprice competition and medicare reimbursement policy", Journal of Health Economics 8(2):147-172.

只找到第二篇和第四篇