IAS Baba Test Series is well known Test Series for UPSC Preliminary Examination. Apart from that, Insights test series is also very helpful. People who cannot afford costly coaching material, for them these two sources are more than enough to crack prelim exam. Be honest with yourself, follow it rigorously, and focus on revision. Here you can download IAS Baba test series for free.
IAS Baba Test Series 2019 pdf in Hindi and English
Here are the download links. This page will update when I will get a new test series on the internet. So be patient.
Download IAS Baba Test Series