  Quarkonium production in proton-proton collision is interesting in profiling
the partons inside the nucleon. Recently, the impact of double parton
scatterings (DPSs) was suggested by experimental data of associated quarkonium
production (J/psi+Z, J/psi+W, and J/psi+J/psi) at the LHC and Tevatron, in
addition to single parton scatterings (SPSs). In this proceedings contribution,
we review the extraction of the effective parameter of the DPS through the
evaluation of the SPS contributions under quark-hadron duality.
