ENGLISH REFERENCES
1. General Vocabulary
Paul, N. (2008). 4000 Essential English words: Book 1. Florida: Compass Publishing.
Paul, N. (2008). 4000 Essential English words: Book 2. Florida: Compass Publishing.
Paul, N. (2008). 4000 Essential English words: Book 3. Florida: Compass Publishing.
Paul, N. (2008). 4000 Essential English words: Book 4. Florida: Compass Publishing.
Paul, N. (2008). 4000 Essential English words: Book 5. Florida: Compass Publishing.
Paul, N. (2008). 4000 Essential English words: Book 6. Florida: Compass Publishing.
2. Grammar
Raymond, M. (2015). Essential grammar in use with answers: A self-study reference and practice book for elementary learners of English (4th ed.). Cambridge: Cambridge University Press.
Raymond, M. (2015). Essential grammar in use with answers: A self-study reference and practice book for intermediate learners of English (4th ed.). Cambridge: Cambridge University Press.
Raymond, M. (2015). Essential grammar in use with answers: A self-study reference and practice book for advanced learners of English (4th ed.). Cambridge: Cambridge University Press.