Thanks for your quick reply, ive been having a hard time with the differences between Kaplan and the USMLE world and which one i should follow. I know USMLE world its more updated, but for purposes of the test its difficult to know which one to follow cause sometimes they say in Kaplan that some guidelines arent changed because it takes time to let everyone know the new guidelines. I ve heard that First Aid is good but everytime i have a doubt, i cant find anything about it on this book. Well thanks anyway. Good day and good luck to everyone preparing for any test of the USMLE.