Retnaningtyas, L., S. Sudarmo, A. Harsono, and S. Damanik. “Effect of Probiotic on the Fecal SlgA Level in Preterm Infants (A Randomized Double-Blind Placebo Control Study)”. Paediatrica Indonesiana, Vol. 48, no. 4, Aug. 2008, pp. 246-52, doi:10.14238/pi48.4.2008.246-52.