None of the site you give meets Wikipedia requirements for references. Please see WP:V - the editor wishing to add the material is responsible for supplying a credable reference. In  this case, a historical work showing that the symbol was used by the Golden Dawn and NOT some successor organization, Stella Matutina, modern G.D. reconstruction, etc. That is, a book reference, with a page number so other editors can verify it. Per WP:V, any editor may remove uncited additions. The burden of proof is on the editor who wishes to make the addition. In  any case, it doesn't belong at the top of the article! —