From the reviews: "The book is devoted to some class of gravitational theories which are alternatives to Einstein's general relativity. ... The book is fairly complete on its themes. The list of references has 925 entries; many citations are of the years 2000-2003. The book is both, a useful survey and a contribution to current discussions." (Rainer Schimming, Zentralblatt MATH, Vol. 1057 (8), 2005) "The main topic of this book is to give an overview about such generalized scalar-tensor theories which represent gravitation ... . The list of 925 references presents a well-balanced source for research in this field. ... Finally, let me say, that the present book ... is recommended to research libraries ... ." (Hans Jurgen Schmidt, General Relativity and Gravitation, Vol. 37 (8), 2005)