Haspelmath, Martin. 1990. The grammaticization of passive morphology. Studies in Language 14. 25–72.
@article{haspelmath1990,
author = {Haspelmath, Martin},
journal = {Studies in Language},
key = {Haspelmath 1990},
number = {1},
pages = {25–72},
title = {The grammaticization of passive morphology},
volume = {14},
year = {1990}
}