@article{319744,
      author = {Rachlin, Sid. and Friel, Susan N.},
      url = {http://library.usi.edu/record/319744},
      title = {Navigating through number and operations in grades 6-8 /},
      publisher = {The National Council of Teachers of Mathematics,},
      recid = {319744},
      pages = {ix, 161 p. :},
      address = {Reston, VA :},
      year = {2006},
}