I looked in the 5th edition of the Andersen Library source list (that came out in 2000) and the Timber/Black-Eyed Susans Press source list, it's not in either.

Then I saw MAPLES FOR GARDENS makes it sound like it wasn't picked up on and propagated until recently, the Van Gelderens (Esveld) perhaps being the only or nearly only ones having it outside of Germany so far.

Thank You bboy