Algebra 101 - part of the GMAT Math Book
Guide to Sequences and Progressions - thorough explanations of the topics
Manhattan GMAT Challenge Set 2 - 20 of the best MGMAT quant questions available for free
Verbal SC Notes - a good collection to help you prepare
710 (Q47, V41) - what worked and what didn’t
750 (Q47, V47) - my GMAT journey