George , M. ., Nord , K.-E. ., Ronquist , G. ., Hedenstiema , G. ., & Wiklund , L. . (1996). Faecal Microflora and Urease Activity during the First Six Months of Infancy. Upsala Journal of Medical Sciences, 101(3), 233–250. https://doi.org/10.3109/03009739609178923