@article{Mullahy1986,
author = {Mullahy, J. },
title= {Specification and testing of some modified count data models},
year = {1986},
doi = {10.1016/0304-4076(86)90002-3},
journal = {Journal of Econometrics },
volume = {33},
number = {3},
pages = {341--365},
}