1. Aronszajn, N.: La théorie des noyaux reproduisants et ses applications. I. Proc. Camb. Philos. Soc. 39, 133–153 (1943)
2. Aronszajn, N.: Reproducing and pseudo-reproducing kernels and their application to the partial differential equations of physics. In: Studies in Partial Differential Equations. Technical report 5, preliminary note. Harvard University, Graduate School of Engineering, ii+31pp. (1948)
3. Aronszajn, N.: Theory of reproducing kernels. Trans. Am. Math. Soc. 68, 337–404 (1950)
4. Aronszajn, N.: Quadratic forms on vector spaces. In: Proceedings of the International Symposium on Linear Spaces, Jerusalem, pp. 29–87. Jerusalem Academic Press/Pergamon, Jerusalem/Oxford (1961)
5. Bergmann, S.: Über die Entwicklung der harmonische Funktionen der Ebene und des Raumes nach Orthogonalfunktionen. Math. Annalen 86, 238–271 (1922)