Balashov Y. A., Larionov A. N., Gannibal L. F., Sirotkin A. N., Tebenkov A. M., Ryüngenen G. I., and Ohta Y. “An Early Proterozoic U-Pb Zircon Age from an Eskolabreen Formation Gneiss in Southern Ny Friesland, Spitsbergen”. Polar Research, vol. 12, no. 2, Jan. 1993, pp. 147-52, doi:10.3402/polar.v12i2.6710.