There's a similar guy who wrote reference books and it's been decided many of the items in them are fakes and much of the information he provided was bogus, although it was then thought to be true.
Third Reich medals are a minefield. They recently found some of the machine used to produce them during the war, which makes copying them easier, and occasionally there are reports of stores being unearthed with original insignia or envelopes - they flood the market and people are looking at what appears to be brand new merchandise but is just incredibly well preserved.