I have purchase a book from arihant for upsc xam. it included 16 years preliminary solved questions. if you are looking for upsc xam I will suggest you for this book. it has description along with its answer so that it help us to remember easily. price also not too much. its not only help for upsc, any competitive xam you are preparing for, this book going to help you alot. so its my suggestion to all refer this book and read.