The vocabulary used in the Upper Sorbian-German spelling dictionary by Pawoł Völkel (5th edition 2005), the German-Upper Sorbian dictionary of new lexicons by Helmut Jenč, Anja Pohončowa, Jana Šołćina (2006) and (partly) in the terminology booklets of the Witaj- Language Center (1995 - 2016).

For the total of 73,500 Sorbian lexemes available in offline mode, all diffraction forms (a total of over 2.3 million different word forms) are still available in online mode.
It is both a search for Upper Sorbian and German keywords possible.

Detailed information on sources and the license can be found at https://soblex.de/impressum.html