Dautray, R., & Lions, J. (2000). Mathematical Analysis and Numerical Methods for Science and Technology: Volume 3 Spectral Theory and Applications (1st ed. 2000.). Springer Berlin Heidelberg : Imprint: Springer. https://doi.org/10.1007/978-3-642-61529-0

Dautray, Robert, and Jacques-Louis Lions. Mathematical Analysis and Numerical Methods for Science and Technology: Volume 3 Spectral Theory and Applications. 1st ed. 2000. Berlin, Heidelberg: Springer Berlin Heidelberg : Imprint: Springer, 2000. https://doi.org/10.1007/978-3-642-61529-0.

Dautray, Robert, and Jacques-Louis Lions. Mathematical Analysis and Numerical Methods for Science and Technology: Volume 3 Spectral Theory and Applications. 1st ed. 2000. Springer Berlin Heidelberg : Imprint: Springer, 2000. https://doi.org/10.1007/978-3-642-61529-0.