| 528 / | HD | SYNTHETIC RESINS OR NATURAL RUBBERS -- PART OF THE CLASS 520 SERIES |
| * | DD | SYNTHETIC RESINS (Class 520, Subclass 1) {23} |
| 44 | DF | .~ FROM REACTANT HAVING AT LEAST ONE -N=C=X GROUP (WHEREIN X IS A CHALCOGEN ATOM) AS WELL AS PRECURSORS THEREOF, E.G., BLOCKED ISOCYANATE, ETC. {17} |
| 48 | DF | .~.~ Process of polymerizing in the presence of a specified material other than reactant {5} |
| 51 | | .~.~.~ Material contains a phosphorus atom |