Resummation of Large Logarithms in the Charm Structure Function
  We show how one can resum the large logarithms which occur in the charm component of the structure function F_{k,c}(x,Q^2,m_c^2) (k=2,L) taken at three light flavours, in the limit Q^2 \gg m_c^2. This resummation leads to an expression of the above quantity for four light flavours including the charm quark density. The latter is related to the parton densities in the three light flavour number scheme. 
W.L. van Neerven