BibTex format
@article{GURMAN:1973:10.1103/PhysRevLett.31.637,
author = {GURMAN, SJ and PENDRY, JB},
doi = {10.1103/PhysRevLett.31.637},
journal = {PHYSICAL REVIEW LETTERS},
pages = {637--639},
title = {EXISTENCE OF GENERALIZED SURFACE STATES},
url = {http://dx.doi.org/10.1103/PhysRevLett.31.637},
volume = {31},
year = {1973}
}