1. On the eigenvalues of certain Hermitian operators;Widom, Harold;Trans. Amer. Math. Soc.,1958
2. Inversion of Toeplitz matrices;Calderón, Alberto;Illinois J. Math.,1959
3. Inversion of Toeplitz matrices. II;Widom, Harold;Illinois J. Math.,1960
4. A theorem on translation kernels in 𝑛 dimensions;Widom, Harold;Trans. Amer. Math. Soc.,1960
5. Inversion of Toeplitz matrices, III, Notices Amer. Math. Soc. bf 97 (1960) 63.