1. O. Boeddicker, Beitrag zur Theorien des Winkels, Dissertation, Göttingen 1876.
2. O. Boeddicker, Erweiterung der Gausschen Theorie der Verschlingungen, Stuttgart, 1876.
3. M. Bognar, Fundations of linking theory, Akademiai Kiado, Budapest 1992.
4. E. Breitenberger, Gauss und Listing: Topologie und Freundschaft. (German) [Gauss and Listing: topology and friendship] Gauss-Ges. Gvttingen Mitt. No. 30 (1993), 3–56.
5. E. Breitenberger, Johann Benedikt Listing, History of topology, 909–924, North-Holland, Amsterdam, 1999. (“Indeed, Listing was present when Gauss finally closed his eyes shortly after 1 a.m. on 23 February 1855”.)