V. Arnautov/S. Glavatsky/A. Mikhalev: Introduction to the theory
of topological rings and modules. Dekker 1996, 500p. $165.
Seems to be a good introduction, but very expensive.

14382 Joan Hart/Kenneth Kunen: Bohr compactifications of discrete structures.
Fund. Math. 160 (1999), 101-151.