Lars H. Andersen, Iben B. Nielsen, Michael B. Kristensen, Mohamed O. A. El Ghazaly, Stefan Haacke, Mogens Brøndsted Nielsen, Michael Åxman Petersen,
Absorption of schiff-base retinal chromophores in vacuo. Journal of the American Chemical Society. ,vol. 127, pp. 12347- 12350 ,(2005) ,
10.1021/JA051638J