Graham, J. B., Wegner, N. C., Miller, L. A., Jew, C. J., Lai, N. C.,
Berquist, R. M., Frank, L. R. & Long, J. A., 2014: Spiracular air breathing
in polypterid fishes and its implications for aerial respiration in stem
tetrapods
–Nature Communications: Vol. 5, [doi: 10.1038/ncomms4022]
http://www.nature.com/ncomms/2014/140123/ncomms4022/full/ncomms4022.html