3Lee D H, Hyun D H, Gwon S H, et. al. Methed for manufacturing dicyclic phosphorus melamine compounds having superior fire retardancy and fire retardant material using thereof. US P 0236132 (2004)
4Philip M P, Richard H, Turley J, et. al. Process for preparing tetrakis ( 2-haloalkyl ) alkylene diphosphates . US P 3803272 ( 1974 )