@article{Smith2003,
author = {Smith, H.L.},
title= {Some thoughts on causation as it relates to demography and population studies},
year = {2003},
doi = {10.1111/j.1728-4457.2003.00459.x},
journal = {Population and Development Review},
volume = {29},
number = {3},
pages = {459--469},
}