Pattern Recognition and Machine Learning, Christopher M. Bishop, 2006 (Springer) - This standard text offers a full presentation of Variational Inference, covering the ELBO, mean-field approximation, and its mathematical derivation.
Variational Inference: A Review for Statisticians, David M. Blei, Alp Kucukelbir, Jon D. McAuliffe, 2017Journal of the American Statistical Association, Vol. 112 (Taylor & Francis)DOI: 10.1080/01621459.2017.1285773 - This review offers an accessible yet precise discussion of variational inference, covering the mean-field framework, its theoretical background, and various uses.
An Introduction to Variational Methods for Graphical Models, Michael I. Jordan, Zoubin Ghahramani, Tommi S. Jaakkola, Lawrence K. Saul, 1999Machine Learning, Vol. 37 (Kluwer Academic Publishers)DOI: 10.1023/A:1007665905271 - This paper establishes variational methods, including the mean-field approximation, as a framework for inference in complex probabilistic models.