Guidelines for blood smear preparation and staining procedure for setting up an external quality assessment scheme for blood smear interpretation. Part I: Control material121, Corrons, J.L. Vives, Albarède S., Flandrin G., Heller S., Horvath K., Houwen B., Nordin G., Sarkani E., Skitek M., and Libeer J.C. , Clin.Chem.Lab Med., 0/0/2004, Volume 42, Issue 8, Number 926, p.922 - 926, (2004)