34Exx | 34D | 34 | 34G |
| 34E05 | Asymptotic expansions |
| 34E10 | Perturbations, asymptotics |
| 34E13 | Multiple scale methods |
| 34E15 | Singular perturbations, general theory |
| 34E18 | Methods of nonstandard analysis |
| 34E20 | Singular perturbations, turning point theory, WKB methods |
| 34E99 | None of the above, but in this section |