I remember that. I think he found them in France. I bought a couple of helmets from him back in the day too. But by the time I got his catalogs, the good ones had been sold. Norm had dies made to reproduce the kokardes and chinstrap fittings, and sold them so you could complete the helmets. He published the first book on spiked helmets in the US, Colonel Rankin's book - which is still one of my favorites - in 1965.
His catalogs of antique firearms, swords, and militaria were amazing, which is not surprising because he was a pretty amazing guy, knowledgable in many fields.