Hoeksma M, Van Rijn M, Verkerk PH, Bosch AM, Mulder MF, de Klerk JB, de Koning TJ, Rubio-Gozalbo E, de Vries M, Sauer PJ, van Spronsen FJ. The intake of total protein, natural protein and protein substitute and growth of height and head circumference in Dutch infants with phenylketonuria. J Inherit Metab Dis. 2005;28(6):845–54. doi: 10.1007/s10545-005-0122-x. PMID: 16435176.