Najmudin, S, Bonifacio C, Duarte AG, Pualeta SR, Moura I, Moura JJG, Romao MJ.  2009.  Crystallization and crystallographic analysis of the apo form of the orange protein (ORP) from Desulfovibrio gigas. Acta Crystallographica Section F-Structural Biology and Crystallization Communications. 65:730-732.