On the Riesz means of the solutions of the Schrödinger equation
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 3, Tome 24 (1970) no. 2, p. 331-348 
@article{ASNSP_1970_3_24_2_331_0,
     author = {Sj\"ostrand, Sigrid},
     title = {On the Riesz means of the solutions of the Schr\"odinger equation},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     publisher = {Scuola normale superiore},
     volume = {Ser. 3, 24},
     number = {2},
     year = {1970},
     pages = {331-348},
     zbl = {0201.14901},
     mrnumber = {270219},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1970_3_24_2_331_0}
}

Sjöstrand, Sigrid. On the Riesz means of the solutions of the Schrödinger equation. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 3, Tome 24 (1970) no. 2, pp. 331-348. http://www.numdam.org/item/ASNSP_1970_3_24_2_331_0/

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