Examples of fit to the OS dimuon invariant mass distribution in the mass region $2 < m_{\mu^{+}\mu^{-}} < 5$~GeV/$c^{2}$ for $\pt < 20$~\GeVc (left), and $7< m_{\mu^{+}\mu^{-}} < 13$ GeV/$c^{2}$ for $\pt < 15$~\GeVc (right). The \jpsi, $\psi$(2S) and $\Upsilon$(nS) signals are modelled with extended Crystal Ball functions, while the background is described by a pseudo Gaussian with a width increasing linearly with the invariant mass. The fit is performed on the full data sample. The widths of the \psitwos, \upstwos and \upsthrees, for these examples, are fixed to 73 \MeVc, 156 \MeVc~and 161 \MeVc, respectively.