Cavalieri, D., C. Parkinson, P. Gloersen, and H. J. Zwally (1996), Sea ice concentrations from Nimbus-7 SMMR and DMSP SSM/I passive microwave data.,
Digital media, National Snow and Ice Data Center, Boulder,
http://nsidc.org/data/nsidc-0051.html, updated 2008
Meier, W., F. Fetterer, K. Knowles, M. Savoie, M. J. Brodzik (2006), Sea ice concentrations from Nimbus-7 SMMR and DMSP SSM/I passive microwave data,
Digital media, National Snow and Ice Data Center, Boulder,
http://nsidc.org/data/nsidc-0051.html, updated quarterly