Sentence:  In 1892 his<nowiki>[</nowiki>Kazimierz Twardowski's<nowiki>]</nowiki> dissertation on Descartes, "Idee und Perception", appeared and was followed in 1894 by his <WSD>habilitation</WSD> thesis, "Zur Lehre vom Inhalt und Gegenstand der Vorstellungen". 
Meaning of the word marked with <WSD> tags:  An academic qualification, prerequiring a PhD, required in order to gain tenure as a professor in some European universities; a thesis or dissertation presented to achieve the qualification.