> 85-XX Astronomy and astrophysics

85-00 General reference works (handbooks, dictionaries, bibliographies, etc.)	85-01 Instructional exposition (textbooks, tutorial papers, etc.)	85-02 Research exposition (monographs, survey articles)
85-03 Historical (must also be assigned at least one classification number from Section 01)	85-04 Explicit machine computation and programs (not the theory of computation or programming)	85-05 Experimental work
85-06 Proceedings, conferences, collections, etc.	85-08 Computational methods	85-99 Astronomy and astrophysics (not classified at a more specific level)
85A04 General	85A05 Galactic and stellar dynamics	85A15 Galactic and stellar structure
85A20 Planetary atmospheres	85A25 Radiative transfer	85A30 Hydrodynamic and hydromagnetic problems
85A35 Statistical astronomy	85A40 Cosmology	85A99 Miscellaneous topics

85-XX Astronomy and astrophysics