Source: http://www.lsis.org/liz/Yves%20Granjon%20Automatique%20-%20Syst%C3%A8mes%20lin%C3%A9aires,%20non%20lin%C3%A9aires%20-%202e%20%C3%A9dition%20Cours%20et%20exercices%20corrig%C3%A9s.pdf