no. 2

The spectrum of operators on L p (E n )
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 3, Tome 24 (1970) no. 2, pp. 201-207. 
@article{ASNSP_1970_3_24_2_201_0,
     author = {Schechter, Martin},
     title = {The spectrum of operators on $L^p (E^n)$},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {201--207},
     publisher = {Scuola normale superiore},
     volume = {Ser. 3, 24},
     number = {2},
     year = {1970},
     zbl = {0199.15902},
     mrnumber = {267423},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1970_3_24_2_201_0/}
}
Schechter, Martin. The spectrum of operators on $L^p (E^n)$. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 3, Tome 24 (1970) no. 2, pp. 201-207. http://www.numdam.org/item/ASNSP_1970_3_24_2_201_0/

1 Walter Littman, Multipliers in Lp and interpolation, Bull. Amer. Math. Soc. 71 (1965) 764-766. | MR 179544 | Zbl 0156.36504

2 Martin Schechter, Partial differential operators on Lp (En), ibid. 75 (1969) 548-549. | MR 254669 | Zbl 0184.13704

3 Martin Schechter, The spectra of non-elliptio operators, Israel J. Math. 6 (1968) 384-397. | MR 252876 | Zbl 0184.32902

4 F.T. Iha, Spectral theory of partial differential operators, Thesis, University of California, Los Angeles, 1969.

5 F.T. Iha and F.C. Schubert, The spectrucm of partial differential operators on LP (Rn), Trans. Amer. Math. Soc., to appear. | MR 270211 | Zbl 0219.47044

6 Erik Balslev, The essential spectrum of elliptic operators in LP (Rn), ibid 116 (1965) 193-217. | MR 190524 | Zbl 0148.09403