The farthest things in the universe
The third chapter, by Patrick S. Osmar, is about quasars, and how they are used to probe the universe. In the final chapter Hyron Spinrad describes the study of the formation of galaxies, which requires the observation of the most distant galaxies.
The book isn't difficult to follow, but it is a bit more academic than most popular cosmology books. It is also more than ten years out of date in a fast moving field, so I wouldn't recommend it for beginners in the subject. It would be more suited to those who have read some of the popular cosmology books and want to read something which is more related to actual research. In particular the chapters on quasars and early galaxies provide material which tends to be lacking in most popular accounts of the subject.