Die Frage nach der Technik is a small text that is found in several places. In the Gesamtausgabe it is part of VA. It has also been published in a smaller editions called TK. Please be aware of this when using the index.
Heidegger, Martin, ‘Die Frage nach der Technik’, in Vorträge und Aufsätze, ed. by Friedrich-Wilhelm von Herrmann, Martin Heidegger Gesamtausgabe, band 7 (Frankfurt am Main: Vittorio Klostermann, 200AD), pp. 7–36