“Sialic Acids. I. Technic of the Quantitative Determination of N-Acetyl-Neuraminic Acid in Human Serum and Its Normal Values”. Revista Española De Fisiología, vol. 18, no. 1, Mar. 1962, pp. 23-30, https://revistas.unav.edu/index.php/ref/article/view/48966.