Are these books sufficient for GMAT preparation? Or are the excessive?

– Official Guide for GMAT Review 11 and 12
– Official Guide for GMAT Verbal Review
– Official Guide for GMAT Quantitative Review
– Kaplan Premier Book with cd
– Kaplan GMAT 800
– Kaplan GRE & GMAT Math Workbook
– Manhattan GMAT Sentence Correction guide
– Princeton Review

Do i need to buy the math workbook? Or is OG quant enough?