"English Words: History and Structure" by Robert Stockwell, Donka Minkova
The subject of this book is the origin of words in the English language, primarily those borrowed from the classical languages, namely Latin and Greek, either directly, or via French. A secondary theme is the internal structure of English words. Exercises to accompany each of the ten chapters are available to download from the web. The text is very accessible to all levels of reader; no knowledge of linguistics or linguistic terminology is assumed. For the reader unfamiliar with historical linguistics, or the influences which have shaped the English language, it will bring a new dimension to the understanding of the words that form the basis of our language. The once-baffling relationships between pronunciation, spelling, and meaning will become a source of enjoyment in themselves in the light of what can be learned from this book.
"Origins: An Etymological Dictionary of Modern English" by Eric Partridge
A "must have" book.
If you love the English language and are truly very curious about the meanings of its words as reflected in the evolution of its origins and meanings, this is a "must have" book. I have used the 1966 issue of it for years now, and rate it more useful, although a companion book, to the seminal work of Walter Skeat. No library can realistically be said to be complete,nor can any lover of the English language, without both of these works.
Test Your Professional English: Secretarial Ещё один учебник тестов из популярной серии "Test Your..." - на этот раз для офисных работников. Книга содержит 60 тестов и ответы к ним.
This text gives students of English for professional purposes over 500 words and expressions to refer to. It can be used for self-study or in-class. An answer key is provided.
The book is organised into 8 sections and covers over 500 key words and expressions in areas such as the office environment, telephoning, the latest technology, meetings, handling visitors, written communication, and money matters.
Wide variety of tests, including crosswords, cartoons, fill-the-gaps, and many more
Wordweb is a feature rich software that does much more than a paper dictionary or thesaurus. WordWeb is truly a Word Web - each set of synonyms is linked to other related sets. Look up "tree", click on the "Types" tab and you'll have a list of different types of tree. Click on "Part of" and WordWeb will tell you that a tree can be part of a "forest" or "wood".
This is a famous old (1977), but still valuable reference book on English grammar for ESL students. 
Wordweb is a feature rich software that does much more than a paper dictionary or thesaurus. WordWeb is truly a Word Web - each set of synonyms is linked to other related sets. Look up "tree", click on the "Types" tab and you'll have a list of different types of tree. Click on "Part of" and WordWeb will tell you that a tree can be part of a "forest" or "wood".
