We will be using Theoretical Statistics: Topics for a Core Course, by R.W. Keener.
Other standard references that might be useful:
E.L. Lehmann, G. Casella, Theory of Point Estimation
E.L. Lehmann, J.P. Romano, Testing Statistical Hypotheses
A. W. van der Vaart, Asymptotic Statistics
M. Wainwright, High Dimensional Statistics