1. Aoki, M. (1984): “Innovative Adaptation Through the Quasi-Tree Structure: An Emerging Aspect of Japanese Entrepreneurship”. InEntrepreneurship, edited by D. Bös, A. Bergson, and J. R. Meyer, (Zeitschrift für Nationalökonomie/Journal of Economics, Supplementum 4.) Vienna: Springer.
2. Baumol, W., Panzar, J., and Willig, R. (1982):Contestable Markets and the Theory of Industry Structure. New York: Harbrace.
3. Hartwick, J. (1984): “Optimal R & D-Levels when Firmj Benefits from Firmi's Inventive Activity”.Economics Letters 17.: 165–170.
4. Kamien, M., and Schwartz, N. (1972): “Timing of Innovations under Rivalry”.Econometrica 40: 43–60.
5. — (1978): “Self-Financing of an R & D-Project”.American Economic Review 68: 252–261.