What are some sources of knowledge?

Old books that were published before censorship occured

According to Hindu Scriptures, any valid source of knowledge (Pramanam) should pass the following test

1. It should reveal an object not revealed through another source of knowledge. For example the eyes are valid source of knowledge because the reveal colors and forms which cannot be revealed through other sources of knowledge (the ears or smell etc. cannot reveal colors and forms)

2. The knowledge revealed cannot be contradicted by another source of knowledge. The color of an object revealed by the eyes cannot be contradicted by the ears or smell or touch etc.)

3. The knowledge produced should be unambiguous

4. The knowledge produced should be definite (ears revealing sounds without meaning are not a valid source)