Ok, well this formula is for the dilute developer, as in it is ready to use. Moreover, at about 20C, a normal print comes out in 1-2min. It comes from a photography formula book in Bulgarian. According to it, the developer has been(dare I say) developed by a Bulgarian photographer, but as Ian has mentioned above, it's probably a variation of a common formula.However, this one uses sod. bicarbonate, which act as a very good buffer, but one must be careful, as if a too acidic stop may cause bubbles that separate the emulsion from the paper(so I have noticed with old paper).If there's anything else, ask ahead.