SYNTHESIS OF OLIGOMERIC EPOXYCYCLOTRIPHOSPHAZENES AND THEIR PROPERTIES AS REACTIVE FLAME-RETARDANTS FOR EPOXY RESINS ArticleTerekhov I.V., Filatov S.N., Chistyakov E.M., Borisov R.S., Kireev V.V.Phosphorus, Sulfur and Silicon and the Related Elements. Vol. 192. 2017. P.. 544-554