Full functions with an even number of branches - Mitra, Shashanka S.; Porter, Jack R.; Livingston, William R.; Porter, Jack R.; Livingston, William R. (Univ. of Oklahoma, Dep. of Math., 1966)
Enth. u.a.: Porter, Jack R.: A note on common fixpoints for commuting functions. - Livingston, William R.: On the theory of unbounded operators in Hilbert space