This stuff is more focused on earth centered orbits then interplanetary, but the math is the same.
Fundamentals of Astrodynamics by Bate Mueller & White is a great introductory to intermediate level text at a very good price.
I think probably most people working in the field have a copy of "BMW" on their bookshelf. They're coming out with a new edition this fall, more then 40 years after the original - mine is already on order.
Another good one is Methods of Orbit Determination by Escobal - I particularly like to treatment of coordinate systems.
Spacetrack Report Number 3 by Hoots and Roehrich is the foundational work on General Perturbations theory used in the SGP4 propagator for TLE (Two Line Element) data.