Reberšek, Martina, et al. “The Determination of Copper and Other Trace Elements in Serum Samples from Patients With Biliary Tract Cancers: Prospective Noninterventional Nonrandomized Clinical Study Protocol”. Radiology and Oncology, vol. 58, no. 2, June 2024, pp. 300-1, https://radioloncol.com/index.php/ro/article/view/4330.