P3 or P4 (BL3, BL4, L3, L4) containment levels are as specified in the WHO Laboratory Biosafety manual (2nd edition, Geneva 1993).
P3- en P4- (BL3, BL4, L3, L4) inperkingsniveaus zijn gespecificeerd in de WHO Laboratory Biosafety Manual (2e editie, Genève 1993).