Binney and Tremaine, 7.1, 7.4
Binney and Merrifield, 4.6.1
 

Optional reading:

Toomre, A., and Toomre, J. 1972, ApJ 178, 623 - the classic paper that identified peculiar galaxies as mergers

Toomre, A. 1977, in The evolution of galaxies and stellar populations, ed. B. M. Tinsley and R. B. Larson
(New Haven: Yale University Observatory), 401 - the paper that first highlighted the importance of mergers
for the galaxy population as a whole.

Holmberg, E. 1941, ApJ 94, 385 - the first N-body simulation in stellar dynamics

Barnes, J., and Hernquist, L. 1992, ARAA 30, 705 - excellent review of galaxy mergers

Mulder, W. A. 1983, A & A 117, 9 - dynamical friction as the gravitational force from a wake

For a discussion of dynamical friction in spherical systems (as opposed to the unrealistic case of infinite homogeneous systems) see:

Tremaine, S., and Weinberg, M. D. 1984, MNRAS 209, 729
Weinberg, M. D. 1986, ApJ 300, 93