81V05 Strong interaction, including quantum chromodynamics
81V10 Electromagnetic interaction; quantum electrodynamics
81V15 Weak interaction
81V17 Gravitational interaction [See also 83Cxx and 83Exx]
81V19 Other fundamental interactions
81V22 Unified theories
81V25 Other elementary particle theory
81V35 Nuclear physics
81V45 Atomic physics
81V55 Molecular physics [See also 92E10]
81V70 Many-body theory; quantum Hall effect
81V80 Quantum optics
81V99 None of the above, but in this section 

Version of December 15, 1998