IMRAN KHAN

I strongly recommend all the books of Hadley Wickham. Infact, I use his books to teach R programming. I don't know if I could ever learn R programming myself without his books. His books are freely available online. Hadley Wickham' s generosity knows no limits. I have also taught more than 100 students R free of any cost. I got the inspiration from Wickham's generosity. R community owes him a big thanks. If R is now accessible to hundred of thousands R users, it is because of him and his team.