Ansoff, I. (1957). Strategies for diversification. Harvard Business Review, 35 (5), 113-124.
Barney, J. B. (1995). Looking inside for competitive advantage. Academy of Management Executive, 9, 50-81.
David, Fred. R., & David, Forest. R. (2017). Strategic management: A competitive advantage approach (16th ed.). Boston: Pearson.
Henderson, B. (1970). The product portfolio matrix. Retrieved 26 July 2018 from https://www.bcg.com/publications/197...portfolio.aspx.
Learned, E., Christiansen, C., Andrews, K., & Guth, W. (1969). Business policy: Text and cases (Rev. ed.). Homewood, IL: Irwin.
Maier, N. R. F. (1963). Problem-solving discussions and conferences: Leadership methods and skills. NY: McGraw-Hill.
Maier, N. R. F. (1973). Psychology in Industrial Organizations (4th ed.). Boston: Houghton Mifflin.
Porter, M. E. (1980). Competitive strategy: Techniques for analyzing industries and competitors. NY: Free Press.