Keller, Rudi 1995, Zeichentheorie. Zu einer Theorie semiotischen Wissens. Tübingen: Francke.

Peirce, Charles S. 1960, Collected papers of Charles Sanders Peirce. Vols. I-VI ed. by Charles Hartshorne and Paul Weiss, VII-VIII ed. by Arthur W. Burks. Cambridge, Mass.: The Belknap Press of Harvard University Press. 2nd ed.; 1st ed.: 1931-1958.