@misc {MATHEDUC.02418461,
    author       = {Schroeder, M.},
    title        = {Estimation as important topic in the middle grade curriculum. Ueberschlagsrechnung und Schaetzen als Dauerthema im Mathematikunterricht der Realschule.},
    howpublished = {Realschule. (Jul 1988) v. 96(6) p. 223-226. [ISSN 0342-829X]},
    year         = {1988},
    msc2010      = {N23xx},
    identifier   = {1988h.03569},
}