1.
A problem solving approach to mathematics for elementary school teachers / Rick Billstein, Shlomo Libeskind, Johnny W. Lott. Redwood City : The Benjamin a. Cummings Publ. Co., 1990. 945 s. ISBN 0-8053-0390-1.[1, of that borrowed 0]
Slovak Agricultural Library in Nitra
www.slpk.uniag.sk