Hagit Last, Rom Pinchasi. At Least n - 1 Intersection Points in a Connected Family of n Unit Circles in the Plane. Discrete & Computational Geometry, 38(2):321-354, 2007. [doi]
@article{LastP07,
title = {At Least n - 1 Intersection Points in a Connected Family of n Unit Circles in the Plane},
author = {Hagit Last and Rom Pinchasi},
year = {2007},
doi = {10.1007/s00454-007-1341-8},
url = {http://dx.doi.org/10.1007/s00454-007-1341-8},
researchr = {https://researchr.org/publication/LastP07},
cites = {0},
citedby = {0},
journal = {Discrete & Computational Geometry},
volume = {38},
number = {2},
pages = {321-354},
}