On the massless representations of the Poincare groupKõiv, Madis; Loide, Rein-Karl; Ots, Ilmar; Saar, ReinEesti NSV Teaduste Akadeemia toimetised. Füüsika. Matemaatika = Известия Академии наук Эстонской ССР. Физика. Математика = Proceedings of Academy of Sciences of the Estonian SSR. Physics. Mathematics1988 / lk. 397-405 https://www.ester.ee/record=b1264310*est