The next variational prolongation of the Euclidean space
arXiv:1407.4641
Abstract
The unique third-order invariant variational equation in three-dimensional (pseudo)Euclidean space is derived.
8th International Conference of Tensor Society (Varna, Bulgaria, Aug. 22-26, 2005) Corrected after publ.: formula (8), typos pg. 3 MR2363662