I don't want you to think I don't think about these things. 'On' seems a little weird because I think of Pravda as a newspaper* but of course it must be right, since I am looking at it online, and I am sure what I say was on the site wasn't always in the paper.
* Because I am a child of the cold war, you see, so Pravda had a big place in the news every night. In fact, to this day, whenever I hear 'The [di-blah-di-blah-di] AGENCY', my brain immediately short-circuits to, 'comma, TASS,' because that set of words was once so prevalent in my consciousness.**
** I have the same issue with 'The [di-blah-di-blah-di] SERVICE' [comma, ACAS].