  We study charmonium ($c\bar c n\bar n$), bottomonium ($b\bar b n\bar n$) and
exotic ($cc\bar n\bar n$ and $bb\bar n\bar n$) four-quark states by means of a
standard non-relativistic quark potential model. We look for possible bound
states. Among them we are able to distinguish between meson-meson molecules and
compact four-quark states.
