@Article{npg-8-331-2001,
AUTHOR = {Tippett, M. K. and Cohn, S. E.},
TITLE = {Adjoints and low-rank covariance representation},
JOURNAL = {Nonlinear Processes  in Geophysics},
VOLUME = {8},
YEAR = {2001},
NUMBER = {6},
PAGES = {331--340},
URL = {http://www.nonlin-processes-geophys.net/8/331/2001/},
DOI = {10.5194/npg-8-331-2001}
}