Given a case citation, example:
Virsa Singh vs The State Of Punjab 1958 AIR 465
Check Cardiff Index for the jurisdiction.
As this is an Indian case, use Manupatra.
Upon entering Manupatra, click on "Legal Search", and "Indian Citation". Fill in the relevant details as demonstrated below, before clicking "search".
There tends to be multiple results, as cases from the various state courts of India share the same citation. Click on the appropriate one.
You should be able to access the full case.