Relativizing Time, Space, and Time-Space. - Ronald V. Book; Christopher B. Wilson; Xu Mei-Rui (SIAM J. Comput., 1982)

Positive Relativizations of Complexity Classes. - Alan L. Selman; Xu Mei-Rui; Ronald V. Book (SIAM J. Comput., 1983)

Refining Nondeterminism in Relativizations of Complexity Classes - Xu Mei-Rui; John E. Donner; Ronald V. Book (J. ACM, 1983)