@Article{ars-2-253-2004,
AUTHOR = {Bremer, J.},
TITLE = {Investigations of long-term trends in the ionosphere with world-wide ionosonde observations*},
JOURNAL = {Advances in Radio Science},
VOLUME = {2},
YEAR = {2004},
PAGES = {253--258},
URL = {http://www.adv-radio-sci.net/2/253/2004/},
ISSN = {1684-9965}
}