| 507 / | HD | EARTH BORING, WELL TREATING, AND OIL FIELD CHEMISTRY |
| 200 | DF | WELL TREATING {4} |
| 203 | DF | .~ Contains organic component {17} |
| 252 | DF | .~.~ Organic component contains sulfur attached directly or indirectly to carbon by nonionic bonding {2} |
| 256 | DF | .~.~.~ Organic component contains a sulfur attached directly to carbon by nonionic bonding {3} |
| 257 | ![]() | .~.~.~.~ Plural alkyls attached directly to the same sulfur atom or to a chain of sulfur atoms by nonionic bonding |