@article{Birkelund2003,
author = {Birkelund, G.E. and Heldald, J.},
title= {Who Marries whom? Educational Homogamy in Norway},
year = {2003},
doi = {10.4054/DemRes.2003.8.1},
journal = {Demographic Research},
volume = {8},
number = {1},
pages = {1--30},
}