The aim of this book is to help both the students of Philology faculty and those who are interested in linguistics literature. We would like to thank all those whose sources have been used in this book. We are grateful too, to teachers, colleagues and students for their guidance in the preparation of this book. There are certainly short comings in the book we are ourselves responsible for. We hope we will get more valuable comments and suggestions from the concerned in order to improve the quality of the book.