Krohn, Burton. "Calculation of vibration-rotation energies of diatomic molecules to sixth order of approximation and bent symmetrical XY₂ triatomic molecules to fourth order by an improved systematic perturbation procedure /." Doctoral dissertation, Ohio State University, 1971. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486724793023248Chicago Manual of Style (17th edition)