Inclusive hadron electroproduction at HERA at NLO with and without   transverse-momentum constraint
  We study single-hadron inclusive electroproduction in ep scattering at DESY HERA at next-to-leading order in the parton model of quantum chromodynamics endowed with non-perturbative fragmentation functions. Specifically, we consider charged-hadron production, with unspecified transverse momentum p_T, in the Breit frame and D^{*+-} production as a function of p_T, and perform comparisons with recent data from the H1 Collaboration. 
B. A. Kniehl