1Chung CY, Kim D. Are anxiety and depression distinct: exploratory factor analysis of Zung's self- rating anxiety and depression scalesIJ ]. Korean J Biol Psychiatry, 2013, 20(1)." 21- 27.
2Reich A, Heisig M, Phan NQ, et al. Visual analogue scale: evaluation of the instrument for the assessment of pruritus[J]. Acta I)erm Venere- oh 2012, 92(5): 497 501.
3Hawkins JL. Epidural analgesia for labor and delivery:J ]. N Engl J Med, 2010, 362(16): 1503-1510.