Later the following studies appeared concerning quadrisecants: H. Morton and D. Mond: Closed curves with no quadrisecants. In: Topology. v. 21, 1982, pp. 235–243; Greg Kuperberg: Quadrisecants of knots and links. In: J. Knot Theory Ramifications. v. 3, 1994, pp. 41–50 [1]; B. Wiest and M. T. Green: A natural framing of knots. In: Geometry & Topology. v. 2, 1998, pp. 31–64 [2] (additivity of the knottedness invariant) and Elizabeth Denne: Alternating quadrisecants of knots (2005) arXiv:math/0510561.
berlingeschichte.de
Vogt, Annette (1999). "Von der Hilfskraft zur Leiterin: die Mathematikerin Erika Pannwitz" [From assistant to head: the mathematician Erika Pannwitz]. Berlinische Monatsschrift (in German). 8 (5). Department Ideals and Practices of Rationality, Max Planck Institute for the History of Science, Max Planck Society: 8–24.
Ett, Walter; Welk, Reiner (1998). "Zentralblatt für Mathematik und ihre Grenzgebiete". In Begehr, Heinrich; Koch, Helmut; Kramer, Jürg; Schappacher, Norbert; Thiele, Ernst-Jochen (eds.). Mathematics in Berlin. Basel: Birkhäuser. pp. 189–190. doi:10.1007/978-3-0348-8787-8_24. ISBN978-3-0348-8787-8. Zbl0902.01035.
emis.de
Later the following studies appeared concerning quadrisecants: H. Morton and D. Mond: Closed curves with no quadrisecants. In: Topology. v. 21, 1982, pp. 235–243; Greg Kuperberg: Quadrisecants of knots and links. In: J. Knot Theory Ramifications. v. 3, 1994, pp. 41–50 [1]; B. Wiest and M. T. Green: A natural framing of knots. In: Geometry & Topology. v. 2, 1998, pp. 31–64 [2] (additivity of the knottedness invariant) and Elizabeth Denne: Alternating quadrisecants of knots (2005) arXiv:math/0510561.
