@article{Luke2011,
author = {Luke, N. and Clark, S. and Zulu, E.},
title= {The Relationship History Calendar: Improving the Scope and Quality of Data on Youth Sexual Behavior},
year = {2011},
doi = {10.1007/s13524-011-0051-2},
journal = {Demography},
volume = {48},
pages = {1151−1176},
}