@article{Bradley2014,
author = {Bradley, S.E.K. and Casterline, J.B.},
title= {Understanding unmet need: History, theory, and measurement},
year = {2014},
doi = {10.1111/j.1728-4465.2014.00381.x},
volume = {45},
number = {2},
pages = {123--150},
}