Não informado. (1969). Industrial and Commercial Training. J. Wellens, Industrial and Technical Training.
Chicago-referens (17:e uppl.)Não informado. Industrial and Commercial Training. Guilsborough, Inglaterra: J. Wellens, Industrial and Technical Training, 1969.
MLA-referens (8:e uppl.)Não informado. Industrial and Commercial Training. J. Wellens, Industrial and Technical Training, 1969.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.