Isoperimetric numbers and spectral radius of some infinite planar graphs Bojan Mohar (1992) Mathematica Slovaca
Isoperimetric Regions in Rnwith Density rp Wyatt Boyer, Bryan Brown, Gregory R. Chambers, Alyssa Loving, Sarah Tammen (2016) Analysis and Geometry in Metric Spaces We show that the unique isoperimetric regions in Rn with density rp for n ≥ 3 and p > 0 are balls with boundary through the origin.