Array ( [0] => Array ( [title] => L1A [link] => https://www.youtube.com/embed/KzWRTQt0TOU ) [1] => Array ( [title] => L1B [link] => https://www.youtube.com/embed/JjUOqlKoC3Q ) [2] => Array ( [title] => L1C [link] => https://www.youtube.com/embed/Rkzp-wc3nGc ) ) 國立清華大學開放式課程OpenCourseWare(NTHU, OCW) - 第1R講 The Sign of Gauss Curvature