Through the journey of GMAT encountered few books that hoped to study someday.However the books were too expensive/too thick which prevented the purchase. These books have been claimed to be helpful at various dark alleys of GMAT/LSAT forums/Blogs. Mentioning the books for someone who wants to go full throttle/over prepare that is those who want to be GMAT tutors

. I am mentioning where I heard about the book
Sentence CorrectionGrammar by Diagram: Understanding English Grammar Through Traditional Sentence Diagramming
https://www.goodreads.com/review/show/141042825Reference: Amazon Reviewer/Some GMAT forum not able to recall
This book also has a workbook, be careful not to confuse between text book and workbook.
Critical ReasoningCritical Thinking: An Appeal to Reason
Reference: TLS Forum (LSAT forum)
https://www.amazon.com/Critical-Thinking-Appeal-Peg-Tittle/dp/0415997143Reading ComprehensionExercise Your College Reading Skills: Developing More Powerful Comprehension (Paperback) by Janet Elder, Elder Janet
Reference: Amazon Reviewer
https://www.amazon.com/Exercise-Your-College-Reading-Skills/dp/007256380X/ref=sr_1_10?s=books&ie=UTF8&qid=1359113167&sr=1-10