Editions of the letters to and from Beethoven
Standard English-language edition of the letters: "Anderson"
The Letters of Beethoven. Compiled, translated and edited by Emily Anderson. 3 vols. London: Macmillan, 1961.
A number after Anderson normally refers to the number of the letter in her edition. There are a number of problems with Anderson: it was largely her own work; the translations are set in a "timeless English prose" rather than being as literal as possible; and she made significant errors. Since 1961, many new letters have appeared; some of these are found in Albrecht's book.
Ludwig van Beethoven. Briefwechsel Gesamtausgabe. Sieghard Brandenburg, ed. Munich: G. Henle Verlag. 1996.
The most recent German critical edition of the letters was prepared by the Beethoven-Haus, Bonn. This edition replaces Emily Anderson's edition as the standard critical edition. Eight volumes, including an index volume, have been published to date. An additional volume with supplementary material is planned.
Theodore Albrecht, ed. Letters to Beethoven, 3 vols. Lincoln: Univ. of Nebraska Press, 1996.
The first collection of all of the letters known to have been written to Beethoven. This is a very reliable and fact-filled source that is a fascinating read. It also contains translations of over 70 letters of Beethoven which are not included in Anderson.
For other editions of Beethoven's correspondence, search in the Beethoven Gateway in the Category index (search terms: letters from Beethoven; letters to Beethoven). For discussions of specific letters, enter the letter number from the Anderson collection (e.g. Anderson L289 or Brandenburg no. 301) in the Major Subject or Subject indexes.