@book{ BA89789123, author = "Posamentier, Alfred S. and Krulik, Stephen and Hauptman, Herbert Aaron", title = "Problem-solving strategies for efficient and elegant solutions, grades 6-12 : a resource for the mathematics teacher", publisher = "Corwin Press", year = "2008", edition = "2nd ed", URL = "https://ci.nii.ac.jp/ncid/BA89789123" }