Janev, RK., Joachain, CJ., & Nedeljkovic, NN. (1982). Molecular-energy Splitting of Highly Excited-states in the 2-coulomb-center Problem. Physical review. A, Atomic, molecular, and optical physics, 26(1), 116-124. https://doi.org/10.1103/PhysRevA.26.116 (Original work published 1982)