gs for pre

well for preliminary test paper 2 is the key to qualify... which need great practice of comprehensions and quantitative aptitude....
for paper one we need ncerts from class 9th to 12th... its very hard to download and upload each so u can please download from the link
http://ncert.nic.in/ncerts/textbook/textbook.htm
here download all the ncerts as each of dem are usefull for you...

i am sharing link of notes of upsc topper Ghanshyam thori
https://docs.google.com/file/d/0B-5WdSFmy5ZrYzZkNjE1ODktYmRkNS00MGVmLWJkNDQtODE4ODdkYTQ0YTk4/edit?pli=1

you can also visit his blog at
http://ghanshyamthori.blogspot.in/