The 504 Absolutely Essential Words is a language study program directly on your android handset.
Features :
1- Study Section based on the method of this book.(1-words , 2-reading 3-examples)
2- FlashCards Section based on Leitner's system.
3- Search Section to search in words, definitions or examples.
4- Help Section to know how to work with flashcards section, etc.
5- the main style of the project changed.

This Book book has faced a great approval between English learners who want to improve their vocabulary.\nThis book is the latest edition of a proven English vocabulary supplementary etxt for ESL and remedial English courses. Forty-two lessons each introduce twelve new words in sample sentences and short, entertaining articles. Frequent word repetition helps students master these 504 words that are basic to every educated person\'s vocabulary. Self-testing exercises in fill-in-the-blanks format are a part of every lesson.

It is written by   Murray Bromberg (Author), Julius Liebb (Author), Arthur Traiger (Author) and it is published in Barron's Educational Series.