I'm looking for seventeenth-century manuscripts that may have provided the basis for a 1736 print claiming to present a text from 1607 (see http://digital.slub-dresden.de/id347703682 for a scan). As I've found the title mentioned in another manuscript dating to 1607 and a print from 1618, I'm reasonably sure that this claim is accurate but would still love to find earlier manuscripts to back it up further.
Variant spellings I've encountered include 'Das Guldene Flüß' and 'Das Gülden Fluß', though further possibilities are to be expected. The complete title as given in the 1736 print reads: Das Güldne Vließ, Oder Das Allerhöchste, Edelste, Kunstreichste Kleinod, und der urälteste verborgene Schatz der Weisen ('The Golden Fleece or the Highest, Most Noble, Most Artful Gem and the Most Ancient, Hidden Treasure of the Wise').
Please let me know if you've come across any references to such manuscripts.
The attribution to Johann Ambrosius Siebmacher (apparently indeed, the author of the famous Wappenbuch of 1597) is intriguing. He is also supposed to have written Das Wasserstein des Weisens, the key authority for Boehme and 18th c. Rosicrucians. But the attribution in both cases seems to be quite late, with early editions being anonymous.