SAT Resources:

Official SAT Study Guide (2016 Edition) (Official Study Guide for the New Sat) 

The New Math SAT Game Plan: The Strategic Way to Score Higher: Best for students who want to score 550+

CrushTheTest SAT Math Prep: Hard Questions for 700+

SAT Practice Tests

IELTS Resources:

Target Band 7: IELTS Academic Module - How to Maximize Your Score (second edition)

The Official Cambridge Guide to IELTS Student's Book with Answers with DVD-ROM (Cambridge English)

IELTS Practice Tests

TOEFL Resources

Official Guide to the TOEFL Test With CD-ROM, 4th Edition (Official Guide to the Toefl Ibt)

TOEFL Practice Tests  

MATH resources

Mastering Essential Math Skills: 20 Minutes a Day to Success, Book 2: Middle Grades/High School

Secrets of Mental Math: The Mathemagician's Guide to Lightning Calculation and Amazing Math Tricks

English Resources

The Only Grammar Book You'll Ever Need: A One-Stop Source for Every Writing Assignment

Compelling American Conversations: Questions and Quotations for Intermediate American English Language Learners

Practice Makes Perfect English Sentence Builder (Practice Makes Perfect Series)