  The paper describes two Monte Carlo codes dedicated to muon simulations:
MUSIC (MUon SImulation Code) and MUSUN (MUon Simulations UNderground). MUSIC is
a package for muon transport through matter. It is particularly useful for
propagating muons through large thickness of rock or water, for instance from
the surface down to underground/underwater laboratory. MUSUN is designed to use
the results of muon transport through rock/water to generate muons in or around
underground laboratory taking into account their energy spectrum and angular
distribution.
