1 ene 1960 año - By the 1960s, overhead projectors were commonly used in schools.
Descripción:
By mailer_diablo (Self-taken (Unmodified)) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia CommonsAñadido al timeline:
fecha:
1 ene 1960 año
Ahora mismo
~ 64 years ago
