@article{Li2013,
author = {Li, Nan and Lee, Ronald D. and Gerland, Patrick},
title= {Extending the Lee–Carter method to model the rotation of age patterns of mortality-decline for long-term projection},
year = {2013},
doi = {10.1007/s13524-013-0232-2},
volume = {50},
pages = {2037--2051},
}