Németh, A. B. “Conjugate Point Classification With Application to Chebyshev Systems”. Rev. Anal. Numér. Théorie Approximation 3, no. 1 (February 1, 1974): 73–78. Accessed April 25, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1974-vol3-no1-art9.