Pelago, maybe I'm wrong,but I wuld attach no value to it being cited in a book sans vvg paperwork attributing it to a noted German soldier.
Also, nearly all German WWII manufacturers started at serial #1 thru 9999, then started all over again with an A suffix, repeated with B & so on. We had a cherry 1916 DWM P08, that was 3 digit with an A suffix, but understood their serial #'ing.
Walther on their PP's & PPK models didn't repeat the series, started PP serial #'s at 750,000 then ran a little past 1,000,000 then started again at serial # 100,000 to end of WWII production, but the P38 did 1-9999 etc
be safe, enjoy life, journey well
OFC, Mo. Chapter