W. Nährer, and M. Amelang. Lehr- und Forschungstexte Psychologie Springer Verlag, Berlin Heidelberg, eBook edition, (2013)Speed and quality as dimensions of cognitive performance.
J. Heiberg (Eds.) Bibliotheca scriptorum graecorum et romanorum teubneriana (BT) In Aedibvs B.G. Tevbneri MCMLXXII, Stvtgardiae, Editio stereotypa editionis anni MCMX edition, (1972)