http://www.cs.utexas.edu/users/inderjit/public_papers/tr03-07.pdf (Publisher version)
Banerjee, A., Dhillon, I., Ghosh, J., & Sra, S.(2003). Expectation Maximization for Clustering on Hyperspheres (TR-03-07). Austin, TX, USA: University of Texas: Department of Computer Science.