In the theory of functions of several complex variables he introduced the concept of pseudoconvexity[b] during his investigations on the domain of existence of such functions: it turned out to be one of the key concepts of the theory.
Levi, Eugenio Elia (1911), "Sulle ipersuperficie dello spazio a 4 dimensioni che possono essere frontiera del campo di esistenza di una funzione analitica di due variabili complesse" [On the hypersurfaces of the 4-dimensional space that can be the boundary of the domain of existence of an analytic function of two complex variables], Annali di Matematica Pura ed Applicata, s. III (in Italian), XVIII (1): 69–79, doi:10.1007/BF02420535, JFM42.0449.02. Another important paper in the theory of functions of several complex variables, investigating further the theory started in (Levi 1910).
Levi, Eugenio Elia (1959–1960), Opere [Collected works] (in Italian), Roma: Edizioni Cremonese (distributed by Unione Matematica Italiana), pp. XX + 418 (Volume I), 448 (Volume II), MR0123464, Zbl0091.00108. His "Collected works" in two volumes, collecting all the mathematical papers of Eugenio Elia Levi in a revised typographical form, both amending typographical errors and author's oversights. A collection of all his published papers (in their original typographical form), probably an unordered uncorrected collection of offprints, is available online at the Internet Archive: Levi, Eugenio Elia, Mathematical papers, Los Angeles: UCLA, p. 782, archived from the original on 9 August 2016.
^This section is mainly based on the survey article by Picone (1959) included in Levi's "Opere (Collected works)", describing his researches briefly but comprehensively; occasionally, also the comments of Guido Fubini in (Fubini & Loria 1918) are taken into account.
^See the two well known papers (Levi 1910) and (Levi 1910): Levi deals with functions of two complexvariables, but his calculations can be extended to functions with any finite number of variables, as he explicitly states. Levi, following a then well established practice, does not use Wirtinger derivatives.
References
Biographical and general references
Celli, Andrea; Mattaliano, Maurizio, eds. (2015), Eugenio Elia Levi, le speranze perdute della Matematica italiana (in Italian), Milano: EGEA, pp. LIV+326, ISBN978-88-2384-461-2. Wide source of unpublished manuscript documents of and about E.E. Levi. A short presentation could be found on EGEA website
Coen, Salvatore (1999), "Beppo Levi: una biografia", in Levi, Beppo (ed.), Opere. Volume I: 1897–1926 [Collected works. Volume I:1897–1926] (in Italian), Bologna: Edizioni Cremonese (distributed by Unione Matematica Italiana), pp. XIII–LIV, Zbl1054.01520. An ample biographical paper (nearly 40 pages) on Beppo Levi: an earlier version of it was published as Coen, Salvatore (1994), "Beppo Levi: la vita", in Coen, Salvatore (ed.), Seminari di geometria, Università di Bologna, Italia, 1991–1993 (in Italian), Bologna: Università degli Studi di Bologna, Dipartimento di Matematica, pp. 193–232, MR1265762, Zbl0795.01022. It gives many useful information on the family and on the relationship between the two Levi brothers.
Loria, Gino (1918), Panegirico di un Eroe. Commemorazione del Prof. Eugenio Elia Levi pronunziata nell'aula magna dell'Università di Genova addì XXIX maggio MCMXVIII [Panegyric of a Hero. Commemoration of Prof. Eugenio Elia Levi pronounced in the auditorium of the University of Genoa on 29 May 1918] (in Italian), Sestri Ponente: S. L. A. G. / Bruzzone e C., p. 31. A pamphlet containing the commemoration of Eugenio Elia Levi pronounced by Gino Loria at the University of Genova on May 29, 1918.
Padoa, Alessandro (December 1917), "Eugenio Elia Levi", Bollettino della Mathesis (in Italian), 9: 89–92.
Picone, Mauro (1959), "Sulla Vita e sulle Opere di Eugenio Elia Levi", in Levi, Eugenio Elia (ed.), Opere. Volume I [Collected Works] (in Italian), Roma: Edizioni Cremonese (distributed by Unione Matematica Italiana), pp. V–XV, MR0123464, Zbl0091.00108. A commemorative paper on Eugenio Elia Levi written by Mauro Picone and included in the first volume of his Opere (Levi 1959–1960).
Tricomi, G. F. (1962), "Eugenio Elia Levi", Matematici italiani del primo secolo dello stato unitario [Italian mathematicians of the first century of the unitary state], Memorie dell'Accademia delle Scienze di Torino. Classe di Scienze fisiche matematiche e naturali, series IV (in Italian), vol. I, p. 120, Zbl0132.24405, archived from the original on 29 December 2016, retrieved 28 December 2016. Available from the website of the Società Italiana di Storia delle Matematiche. An ample historical paper written by Francesco Tricomi to commemorate all Italian mathematicians who worked during the first century of the Italian State.
Vitali, Giuseppe (December 1917), "Eugenio Elia Levi", Bollettino della Mathesis (in Italian), 9: 86–89.
Dell'Aglio, L. (2005), "LEVI, Eugenio Elia", Enciclopedia Treccani, Dizionario Biografico degli Italiani (in Italian), vol. LXIV, retrieved 15 September 2011. The biographical entry about Eugenio Elia Levi in the "Dizionario Biografico degli Italiani (Biographical Dictionary of Italians)" section of the Enciclopedia Treccani.