<Ul> <Li> Gravitational collapse of a cloud </Li> <Li> Supernova explosions </Li> <Li> Stellar winds </Li> <Li> Expansion of H II regions </Li> <Li> Magnetohydrodynamic waves created by supernova remnants </Li> </Ul> <Li> Gravitational collapse of a cloud </Li> <Li> Expansion of H II regions </Li> <Li> Magnetohydrodynamic waves created by supernova remnants </Li>

Where do we find most of the interstellar material