@Article{angeo-24-173-2006,
AUTHOR = {Voiculescu, M. and Virtanen, I. and Nygr\'en, T.},
TITLE = {The F-region trough: seasonal morphology and relation to interplanetary magnetic field},
JOURNAL = {Annales Geophysicae},
VOLUME = {24},
YEAR = {2006},
NUMBER = {1},
PAGES = {173--185},
URL = {https://angeo.copernicus.org/articles/24/173/2006/},
DOI = {10.5194/angeo-24-173-2006}
}