The recipe is according to the recipe in Valentin Vodnik’s Kuharske bukve adapted to present time. Kuharske bukve is the first cookbook in Slovene language, issued in 1799. Vodnik’s soft pretzels are written on page 101, under recipe number 163.
Resource: Valentin Vodnik, 1799: Kuharske bukve, Lublana: Kleinmajerji skusi saklado Andrea Gassler na tergi Nro. 190, str. 101.