Insley SJ, Robson BW, Yack T, Ream RR, Burgess W Acoustic determination of activity and flipper stroke rate in foraging northern fur seal femalesEndangered Species Research 4:147-155
http://www.int-res.com/abstracts/esr/v4/n1-2/p147-155/
Full text in pdf format <http://www.int-res.com/articles/esr2008/4/n004p147.pdf>
