Zafar D Usmanov is a leading specialist in the field of differential equations. He graduated from Moscow State University in 1959, defending his candidate thesis in 1966 and his doctorate in 1973. He became Professor of Applied Mathematics at Tajik State University in 1983. Since 1981 he has been a full member of the Tajik Academy of Sciences and in 1988 he became Director of the Institute of Mathematics of the Tajik Academy of Sciences. He has published numerous papers on the subject of this book and has written three other books on applied mathematics.