Popular Lectures on Astrophysics
NPTEL Astrophysics & Cosmology Video Lectures - Prof. Somnath Bharadwaj, IIT Kharagpur
Extragalactic Astronomy and Cosmology Lecture Notes - Prof. Barry F. Madore, Carnegie Institution for Science
Digital Library of Astrophysics Research Articles
1. SAO/NASA Astrophysics Data System (ADS)