Blandow, Dietrich. The Experience of GRD in the teaching of science and technology and productive work/ by Dietrich Blandow; Erwin Messner. - Berlin : University College of Education, 1987. - 62 p.; 20 cm. retrs., fot. No. de Clasificación Universal Decimal: 371.13: 5:6 (430.2) =201987 BLA.