Array ( [0] => Array ( [title] => L15A [link] => https://www.youtube.com/embed/WQqooYlWQsY ) [1] => Array ( [title] => L15B [link] => https://www.youtube.com/embed/yd2baZ3TM9k ) ) 國立清華大學開放式課程OpenCourseWare(NTHU, OCW) - Lecture 15 | Center manifolds(proof)