While there's no real "canon" defined for DB, things which Toei came up with are mostly considered canon to the anime at best. Manga-canon (which, we could say is the most canon thing DB has, as it's the original thing) is the kanzenban release of DB manga and the information regarding manga only, provided in the guidebooks.
Bardock - The Father of Goku (going by FUNi's naming) is probably anime-canon, as it doesn't contradict anything in the anime (the same way The History of Trunks doesn't contradict the anime, although contradicts the manga) and Episode of Bardock seems to be a continuation of that special, so it's unclear if it's canon to the anime or not.