@MISC{DIFF_1.MIZ,
  AUTHOR = {Li, Bo and Zhang, Yan and Liang, Xiquan},
  TITLE = {Difference and Difference Quotient},
  DAY = {29},
  MONTH = {September},
  YEAR = {2006},
  ADDRESS1 = {Qingdao University of Science\\and Technology\\China},
  ADDRESS2 = {Qingdao University of Science\\and Technology\\China},
  ADDRESS3 = {Qingdao University of Science\\and Technology\\China},
  SUMMARY = {In this article, we give the definitions of forward difference,
  backward difference, central difference and difference quotient,
  and some of their important properties.}}

