The first edition of Gramsci’s writing has been published in Turin by Einaudi.

Political writing (during the pre-prison period):
L’Ordine Nuovo 1919-1920 (1954)
Pre-Prison Writing 1914-1918 (1958)
Under the Millstone 1916-1920 (1960)
Socialism and Fascism. L’Ordine Nuovo 1921-1922 (1966)
Building the Communist Party 1923-1926 (1971)
Turin Chronicles 1913-1917, edited by S. Caprioglio (1980)
The Future City 1917-1918, edited by S. Caprioglio (1982)
Our Marx 1918-1919, edited by S. Caprioglio (1984)
L’Ordine Nuovo 1919-1920, edited by V. Gerratana and A.A. Santucci (1987).

The first edition of the Prison Notebooks were printed in volumes by subject:
Historical Materialism and the Philosophy of Benedetto Croce (1948)
Intellectuals and Cultural Organisation (1949)
The Risorgimento (1949)
Notes on Machiavelli, Politics and the Modern State (1949)
Literature and National Life, 1950
Past and Present (1951)
Later, in the critical edition by the Gramsci Institute:
Prison Notebooks, edited by V. Gerratana, 4 vols., 1975.

His correspondence from prison has been published in various editions.
Letters from Prison (1947)
Letters from Prison, edited by S. Caprioglio and E. Fubini, 1965
Letters from Prison, edited by A.A. Santucci, 2 vols., Palermo, Sellerio, 1996.
Among the partial editions, important ones are:
A. Gramsci, T. Schucht, Letters 1926-1935, edited by A. Natoli and C. Daniele, 1997

The Gramsci Foundation ONLUS is working on the National Edition of the Writings of Antonio Gramsci, established by the Ministry for Cultural Heritage in 1996, now directed by Giuseppe Vacca. The volumes were published by the Italian Encyclopaedia Institute. Published works to date:
Prison Notebooks, 1, Translation Notebooks (1929-1932), edited by G. Cospito and G. Francioni (2007)
Documents, 1, Notes on Linguistics 1912-1913, edited by G. Schirru (2016)
Writings, 2, 1917, edited by L. Rapone (2015)
Letters, 1, January 1906 – December 1922, edited by D. Bidussa, F. Giasi, G. Luzzatto Voghera and M.L. Righi (2009)
Letters, 2, January-November 1923, edited by D. Bidussa, F. Giasi and M.L. Righi (2011)

The Gramsci Foundation ONLUS has the Gramsci archives.
See the Foundation’s website (www.fondazionegramsci.org) for the Gramsci Bibliography. Founded by John M. Cammett, now edited by Francesco Giasi and Maria Luisa Righi, this Bibliography contains the titles of all writing on Gramsci since 1922 and all the translations of his works, for a total of more than 20,000 items in 41 languages.