University of St. Andrews (UK)
University of St. Andrews: Gabriel Cramer
Information about the life of Gabriel Cramer (1704-1752 CE), 18th century mathematician credited with "Cramer's Rule," though "Cramer was certainly not the first to give this rule."
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Sistemas De Cramer Interpretacion Geometrica
In Spanish. In this unit you will be able to visually Cramer's rule with interactive activities.