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