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Alerstam E, Svensson T, Andersson-Engels S, Spinelli L, Contini D, Dalla Mora A, Tosi A, Zappa F, Pifferi A.Alerstam E, et al.Opt Lett. 2012 Jul 15;37(14):2877-9. doi: 10.1364/OL.37.002877.Opt Lett. 2012.PMID: 22825164