1. Ch. Badelt, and P. Weiss: ?Non-Profit Organizations and Government Organizations in Social Services - Empirical Evidence for Austria ?, paper presented at the International Conference on ?Voluntarism, Non-Government Organizations and Public Policy?, Jerusalem, 1989 .
2. H. Hansmann: ?The Role of Nonprofit Enterprise ?,Yale Law Journal, 1980 , pp.835 -898 .
3. E. James: ?Institutional Choice in the Education Industry: Modern and Developing Countries Compared ?, paper presented at the international workshop on ?The Economics of Institutional Choice and Design?, Vienna, 1987 .