  We review the calculations of form factors and coupling constants in vertices
with charm mesons in the framework of QCD sum rules. We first discuss the
motivation for this work, describing possible applications of these form
factors to heavy ion collisions and to B decays. We then present an
introduction to the method of QCD sum rules and describe how to work with the
three-point function. We give special attention to the procedure employed to
extrapolate results obtained in the deep euclidean region to the poles of the
particles, located in the time-like region. We present a table of ready-to-use
parametrizations of all the form factors, which are relevant for the processes
mentioned in the introduction. We discuss the uncertainties in our results. We
also give the coupling constants and compare them with estimates obtained with
other methods. Finally we apply our results to the calculation of the cross
section of the reaction $J/\psi + \pi \rightarrow D + \bar{D^*}$.
