Aparece: Francisco Ziga, "Bibliografía Pedagógica. Libros de texto para enseñanza primaria:1850-1970 V. Libros de Gramática" en Boletín del Instituto de Investigaciones Bibliográficas 1981-1982, Biblioteca Nacional, Hemeroteca Nacional, Universidad Nacional Autónoma de México, Nos. 18 - 19,p. 151.
"In the curriculum of 1941, the working methods for the exam-free middle school were revised as a result of the Schools Act of 1937, although the new work plans for this department in Frederiksberg largely meant a continuation of the guidelines from the plan of 1932, which recommended period reading and summarized subjects in groups. In addition, there were the experiences from the admittedly inadequately completed experimental work with the practical middle school. The result was that a further interconnection of the subjects was recommended for a subject teaching that left the teacher very free from the material he would review in the classes." -- (Tranlated from the introducion)
Aparece: Francisco Ziga, "Bibliografía Pedagógica. Libros de texto para enseñanza primaria: 1850-1970 V. Libro de Geografía" en Boletín del Instituto de Investigaciones Bibliográficas 1981-1982, Biblioteca Nacional, Hemeroteca Nacional, Universidad Nacional Autónoma de México, Nos. 18 - 19, p. 57.
