Ramm AG. Completeness of the set \(\{e^{ik\beta \cdot s}\}|_{\forall \beta \in S^2}\). GJMA [Internet]. 2017 Jul. 15 [cited 2024 Dec. 22];5(2):43-. Available from: https://sciencepubco.com/index.php/GJMA/article/view/7975