Rothschild-Stiglitz working paper?
(Edited)
Here is the working paper. Enjoy.

Rothschild, M., and J. E. Stiglitz, "Equilibrium in Competitive Insurance Markets," Technical Report No. 170, IMSSS Stanford University, 1975.

https://drive.google.com/file/d/1MXb3OcOQc_lxNYC4CzsNTTax9_3Q_4UN/view?usp=sharing