Numerical Optimization, Jorge Nocedal, Stephen J. Wright, 2006 (Springer)DOI: 10.1007/978-0-387-40065-5 - A standard graduate-level textbook offering a comprehensive introduction to optimization algorithms, including a detailed treatment of trust region methods, their theoretical foundations, and practical algorithms.
Trust-Region Methods, Andrew R. Conn, Nicholas I. M. Gould, Philippe L. Toint, 2000 Vol. 1 (MPS-SIAM Series on Optimization) (Society for Industrial and Applied Mathematics)DOI: 10.1137/1.9780898719857 - This authoritative book focuses solely on trust region methods, providing an in-depth analysis of their theory, algorithms, and applications.
The conjugate gradient method and trust regions, Trond Steihaug, 1983SIAM Journal on Numerical Analysis, Vol. 20 (Society for Industrial and Applied Mathematics Publications)DOI: 10.1137/0720042 - This seminal paper introduced the truncated conjugate gradient method for solving the trust region subproblem, widely known as the Steihaug-Toint method.