Every review article or book raises the obvious question about its completeness. In order to give the readers an idea about the degree of completeness of this review, the method used to compile the bibliography is described briefly below. These were the essential steps:

1. The author has been interested in the subject since about 1980. Until 1988, when systematic compilation was begun, I studied every newly published research or review article on inhomogeneous cosmological models, and followed each reference whose context of citation suggested that it might contain more of the relevant material. The latest publications included are those that reached my hands in September 1994.

2. I looked through the subject indexes to all volumes of Physics Abstracts, beginning with the 1915 volume, and studied the sections on cosmology, general relativity, gravitation, gravitational collapse and spacetime configurations. Whenever any keyword of title or abstract suggested that the paper might be relevant for the review, I added the reference to the list of papers to look up. The last index so surveyed was Part I of the 1994 volume.

3. While reading or looking through the papers, I added every reference that seemed relevant to the list.

Stage 3 produced more than 1000 references in addition to about 1000 found in stage 2 (but about two-thirds of the total number of papers were discarded according to the criteria listed in Section 1.1).