From Infogalactic: the planetary knowledge core
Forms of imperfect competition include:
- Oligopoly, in which there are few sellers of a product.
- Monopolistic competition, in which there are many sellers producing highly differentiated products.
- Monopsony, where there are many sellers but only one buyer, and oligopsony, where there are many sellers but few buyers.
- Massimiliano Vatiero (2009), "An Institutionalist Explanation of Market Dominances". World Competition. Law and Economics Review, 32(2):221-6.