Kramer, Horst. “A Helly-Type Theorem for Arcwise Connected Sets in the Plane”. Anal. Numér. Théor. Approx. 6, no. 1 (February 1, 1977): 37–42. Accessed May 19, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1977-vol6-no1-art6.