@Article{acp-7-1333-2007,
AUTHOR = {Laakso, L. and Gagn\'e, S. and Pet\"aj\"a, T. and Hirsikko, A. and Aalto, P. P. and Kulmala, M. and Kerminen, V.-M.},
TITLE = {Detecting charging state of ultra-fine particles: instrumental development and ambient measurements},
JOURNAL = {Atmospheric Chemistry and Physics},
VOLUME = {7},
YEAR = {2007},
NUMBER = {5},
PAGES = {1333--1345},
URL = {http://www.atmos-chem-phys.net/7/1333/2007/},
DOI = {10.5194/acp-7-1333-2007}
}