In this hardcover edition, the author develops the background and fundamental theory of inversion processes used in remote sensing (e.g. atmospheric temperature structure measurements from satellites), starting at an elementary level. The book opens with a number of examples of inversion problems from a wide variety of disciplines and it is shown that mathematically the same problem--solution of a Fredholm linear integral equation of the first kind--is involved in every instance. The reduction of such integral equations to a system of linear algebraic equations is then discussed. Methods for obtaining stable solutions at the expense of introducing constraints in the solutions are discussed and illustrated and the last three chapters elaborate and extend the material developed in preceding chapters. Other inversion procedures are derived, with examples, and a method for detailed analysis of the information content of indirect measurements is provided. Unabridged, corrected Dover republication of the work published as Volume 3 of Developments in Geomathematics by Elsevier Scientific Publishing Company, Amsterdam, 1977. Preface. Suggestions for Further Reading. Name Index. Subject Index. 42 text figures.