@article{A’Hearn2009,
author = {A’Hearn, B. and Baten, J. and Crayen, D.},
title= {Quantifying quantitative literacy: Age heaping and the history of human capital},
year = {2009},
doi = {10.1017/S0022050709001120},
volume = {69},
number = {3},
pages = {783--808},
}