XPS and UPS Studies of Valence Fluctuation and Surface States of Yb<sub>4</sub>As<sub>3</sub>, Yb<sub>4</sub>Sb<sub>3</sub>and Yb<sub>4</sub>Bi<sub>3</sub>S. Suga, T. Kasuya, S.-J. Oh et al.|Journal of the Physical Society of Japan|1989Cited by 43