When one talks about the year associated with a film, it is usually the censor certification year. This is because that is the only official year related to the film Secondly, the two pioneers in film compilation work, Firoze Rangoonwalla and BV Dharap, decided to use this year. This information is published in the official gazettes. The censor information of Hindi films from 1931 to 2010 is available on the website

http://hamraaz.org/hfgk

The other year, or more commonly date that people often mention is the date of the first release of the film. This date varies from city to city as films having limited number of prints, cannot be released everywhere at once. This was specially so in the early years. The film release information is not published in a unique source and requires much more work. One can find it in the magazine reviews, magazine and newspaper ads, and, sometimes in the trade publications. All these sources are hard to come by.
We were lucky to find issues of the Madras edition of the Indian Express online. One of us (MVS) clipped images from the online source and they were published here

http://hindi-films-songs.com/books/IndianExpress-FilmNewsArchive2.html

Here one can follow the life of many famous Indian films in various theatres. One can read the news about the films and their stars and also reviews written at that time. We found this window into the mindset of the film-going people of that bygone era to be enjoyable to work with and fascinating.
We hope that our readers will also enjoy this nostalgia-inspiring work.