| 564 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
| * | DD | ORGANIC COMPOUNDS (Class 532, Subclass 1) {1} |
| 1 | DF | .~ AMINO NITROGEN CONTAINING (E.G., UREA, SULFONAMIDES, NITROSAMINES, OXYAMINES, ETC., AND SALTS THEREOF) {37} |
| 305 | DF | .~.~ Benzene ring containing {24} |
| 437 | DF | .~.~.~ Purification or recovery {2} |
| 438 | | .~.~.~.~ By salt formation |