@article{Portes1999,
author = {Portes, A. and Guarnizo, L.E. and Landolt, P.},
title= {The study of transnationalism: Pitfalls and promise of an emergent research field},
year = {1999},
doi = {10.1080/014198799329468},
volume = {22},
number = {2},
pages = {217--237},
}