What is linguistics? 3rd Edition

Linguistics is supposed a difficult subject for students. This book is a good book for students.It explain about the topics that what is linguistics and what is not linguistics and what are advantages to study the linguistics. The writer gives informations about some other books of linguistics which may be useful for students.I thank that this book is ,also,useful for a common man who want to know primary informations about linguistics ,but it don't satisfy a scholar who want to research about important schools of linguistics or origin of language.