1. Agarwal, P.K., Nevo, E., Pach, J., Pinchasi, R., Sharir, M., Smorodinsky, S.: Lenses in arrangements of pseudo-circles and their applications. J. ACM 51, 139–186 (2004)
2. Albenque, M., Knauer, K.: Convexity in partial cubes: the hull number. Discrete Math. 339, 866–876 (2016)
3. Björner, A., Las Vergnas, M., White, N., Sturmfels, B., Ziegler, G.M.: Oriented Matroids, Encyclopedia of Mathematics and Its Applications, vol. 46, 2nd edn. Cambridge University Press, Cambridge (1999)
4. Bogomolny, A.: Cut-the-knot: four touching circles. http://www.cut-the-knot.org/Curriculum/Geometry/FourTouchingCircles.shtml#Explanation
5. Bokowski, J., Richter, J.: On the finding of final polynomials. Eur. J. Comb. 11, 21–34 (1990)