Roberts, Nicholas W.; Chiou, Tsyr-Huei; Marshall, Nicholas Justin; Cronin, Thomas W. (2009). "A biological quarter-wave retarder with excellent achromaticity in the visible wavelength region". Nature Photonics. 3 (11): 641–644. Bibcode:2009NaPho...3..641R. doi:10.1038/nphoton.2009.189.
Roberts, Nicholas W.; Chiou, Tsyr-Huei; Marshall, Nicholas Justin; Cronin, Thomas W. (2009). "A biological quarter-wave retarder with excellent achromaticity in the visible wavelength region". Nature Photonics. 3 (11): 641–644. Bibcode:2009NaPho...3..641R. doi:10.1038/nphoton.2009.189.