I use Na2S2O4 as reducing agent for one of my reactions, all the papers i found used it as reducing agent (for nitroso uracil derivative), i would ask if someone use other reducing agent for such nitrosoCpd.
it need difficult conditions as my Yields often low.

Unless you want us to hand you a big list of every reducing agent known to man you will have to describe your chemical reaction in detail, including the conditions, and reagents used.