McLachlan, G. J. (2009). Model-based clustering. In Steven D. Brown, Roma Tauler and Beata Walczak (Ed.), Comprehensive chemometrics: chemical and biochemical data analysis (pp. 655-681) Oxford, U.K.: Elsevier Science. doi:10.1016/B978-044452701-1.00068-5
Finite mixture models are being commonly used in a wide range of applications in practice concerning density estimation and clustering. An attractive feature of this approach to clustering is that it provides a sound statistical framework in which to assess the important question of how many clusters are there in the data and their validity.