Johnstone, T. M. 1975. The Modern South Arabian Languages. Afroasiatic Linguistics 1. 93–121.
@article{johnstone1975,
author = {Johnstone, T. M.},
journal = {Afroasiatic Linguistics},
pages = {93–121},
title = {The Modern South Arabian Languages},
volume = {1},
year = {1975}
}