Recommender Systems: An Introduction, Francesco Ricci, Lior Rokach, Bracha Shapira, 2015 (Springer)DOI: 10.1007/978-1-4899-7637-6_1 - This second edition is a standard reference for recommendation systems, covering content-based filtering methods and the construction of user profiles from item features.
Learning and Revising User Profiles for Content-Based Filtering, Michael J. Pazzani, Daniel Billsus, 1997Proceedings of the Fourteenth International Conference on Machine Learning, 1997 (Association for Computing Machinery)DOI: 10.5555/645524.657512 - A foundational paper discussing how to learn and update user profiles for content-based filtering, including aggregation techniques.
Mining of Massive Datasets, Jure Leskovec, Anand Rajaraman, Jeff Ullman, 2014 (Cambridge University Press) - Chapter 9 of this book provides an overview of recommender systems, including content-based methods and the construction of user profiles using item feature vectors.