Paşaoğlu, Hatice, et al. “Analyses of Serum Vitamin D-Binding Protein, Ceruloplasmin and Copper Levels in Preterm Infants”. The Turkish Journal of Pediatrics, vol. 34, no. 4, Oct. 1992, pp. 225-30, https://doi.org/10.24953/turkjpediatr.1992.3738.