• Fundamental solution of the wave equation in case of a curved space-timeMankin, RomiEesti NSV Teaduste Akadeemia toimetised. Füüsika. Matemaatika = Известия Академии наук Эстонской ССР. Физика. Математика = Proceedings of Academy of Sciences of the Estonian SSR. Physics. Mathematics1983 / lk. 351-357 https://www.ester.ee/record=b1264310*est