Bartnik, R. McKinnon, J. 141–144 1988 61 Particlelike Solutions of the Einstein–Yang–Mills Equations print 10.1103/PhysRevLett.61.141 Phys. Rev. Lett. Einstein-Yang-Mills theory Einstein-Yang-Mills theory Mathematical relativity Bartnik-McKinnon solutions Einstein-Yang-Mills equations Einstein-Yang-Mills theory Solitons Uniqueness theorems Einstein-Yang-Mills theory Gauge fields Solitons Yang-Mills theory Bartnik-McKinnon solutions Einstein-Yang-Mills equations Einstein-Yang-Mills theory Mathematical relativity Bartnik-McKinnon solutions Einstein-Yang-Mills equations Bartnik-McKinnon solutions Einstein-Yang-Mills equations