[18] TIMMS, Third International Maths and Science Survey; Ludger Wössmann, Schooling Resources, Educational Institutions and Student Performances: The International Evidence Kiel Working Papers No. 983, Kiel Institute for World Economics, May 2000.
[18] TIMMS, Third International Maths and Science Survey; Ludger Wössmann, Schooling Resources, Educational Institutions, and Student Performance: The International Evidence, Kiel Working Papers No. 983, Kiel Institute for World Economics, mai 2000