Berg, T. M., de Vries, J. A., van Gasteren, C. J., Meeuwissen, H., Stevens, G. A., & Verbon, F. J. (1976). Comparative studies on the microbiological vitamin B12 assay at two laboratories.

Berg, T M., J A. de Vries, C J. van Gasteren, H. Meeuwissen, G A. Stevens, ja F J. Verbon. Comparative Studies On the Microbiological Vitamin B12 Assay At Two Laboratories. 1976.

Berg, T M., et al. Comparative Studies On the Microbiological Vitamin B12 Assay At Two Laboratories. 1976.