Mazzone, AM, et al. “Identification of Cells Secreting a Thymostimulin-Like Substance and Examination of Some Histoenzymatic Pathways in Aging Avian Primary Lymphatic Organs: II. Bursa of Fabricius”. European Journal of Histochemistry, vol. 47, no. 4, June 2009, pp. 325-38, doi:10.4081/843.