Was ist Was
Was ist Was, (scilicet Latine "quod est quod") est signum mercatorium domus editoriae Tessloff. Was ist Was ab anno 1961 constat. Sub illo signo libri, Discus disci versatiles digitales et disci compacti editi sunt.

Nexus externus 
 WAS IST WAS apud Tessloff-Verlag 

Societates editoriae
Constituta 1961
Germania