1. A. Beurling, Sur les intégrales de Fourier absolument convergentes et leur application à une transformation fonctionnelle. Neuvième congrès des mathématiciens scandinaves, Helsingfors (1938), 345–366.
2. E.T. Copson, On a generalisation of monotonic sequences, Proc. Edinburgh Math. Soc. (2) 17 (1970), 159–164.
3. H.G. Diamond and M. Essén, One-sided Tauberian theorems for kernels which change sign. Proc. of the London Math. Soc. (3) 36 (1978), 273–284.
4. M. Essén, Studies on a convolution inequality. Arkiv f. matematik 5 (1963), 113–152.
5. M. Essén, Note on “A theorem on the minimum modulus of entire functions” by Kjellberg. Math. Scand. 12 (1963), 12–14.