In my many years of researching and writing on Handel, the following books have proved invaluable. I have added some notes for those interested in the details:
Burrows, Donald, Handel (Oxford: Oxford University Press, 1994) – despite my own ungenerous, misguided, review on Radio 3, this has proved its value, year after year, as the best of all guides to Handel’s life and music, with detailed background and astute musical analysis.
Burrows, Donald (ed.), The Cambridge Companion to Handel (Cambridge: Cambridge University Press, 1997) – an excellent collection of essays, under the headings ‘Background’, ‘The music’ and ‘The music in performance’, from some of the best Handel scholars of the age.
Dean Winton, Handel’s Dramatic Oratorios and Masques (Oxford: Clarendon Press, 1959) – the standard reference work for Handel’s choral compositions and oratorios.
Dean, Winton, and John Merrill Knapp, Handel’s Operas, 1704-1726, second edition (Oxford: Clarendon Press, 1995) – a brilliant, authoritative, commentary on Handel’s opera career from his earliest German opera to the end of the first period of the Royal Academy; the book gives all the historical information you could ever need, with the best musical analysis available.
Dean, Winton, Handel’s Operas, 1726-1741 (Woodbridge: The Boydell Press, 2006) – the completion of a life’s work, concluding the survey of Handel’s operas until the end of his career; a tour de force and labour of love.
Deutsch, Otto Erich, Handel: A Documentary Biography (London: Charles Black, 1955) – the most important source of sources for Handel scholars; a comprehensive compilation of reviews, letters, journal articles, newspaper features, advertisements and other published material from the period.
Flesch, Siegfried and Berndt Baselt (eds), Händel-Handbuch, Band I –Lebens- und Schaffensdaten / Thematisch-systematisches Verzeichnis: Bühenweke (Leipzig: Veb Deutscher Verlag Für Musik, 1978) – a complete, systematic, catalogue, with musical illustrations of the musical motifs, themes and borrowings for all of Handel’s operas; even for readers without German, easy to follow, and the best means of tracing Handel’s self-sourcing of arias.
Harris, Ellen T. (ed.) The Librettos of Handel's Operas, edited by Ellen T.Harris, 13 vols (Garland Publishing Inc., New York and London, 1989) - this collected edition gives facsimiles of the original publications of the Italian librettos and their translations; sometimes the translation is rather loose, and sometimes arias are not translated in full, but they offer a fascinating opportunity to read the material available to the contemporary audience.
Harris, Ellen, Handel and the Pastoral Tradition (London: Oxford University Press, 1980) – a revelatory study of the pastoral tradition in European music and its influence on Handel’s music.
Heriot, Angus, The Castrati in Opera (London: Secker and Warburg, 1956) – a compelling record of the history of the castrati.
Hogwood, Christopher, Handel (London: Thames and Hudson, 1988) – an account of Handel’s life and work for the general reader, from one of the leading musicologists and performers of baroque period music.
Keates, Jonathan, Handel: The Man and His Music (London: Victor Gollanz, 1985) – one of the best guides of Handel’s life and music for the general reader.
Mainwaring, John, Memoirs of the Life of the Late George Frederic Handel (R. and J. Dodsley: London, 1760) – the most important eighteenth-century biographical source; a wonderful account, full of fascinating and compelling anecdotes.
Marx, Hans Joachim (ed.), An International Handel Bibliography / Internationale Händel-Bibliographie: 1959-2009 (Göttingen: Vandenhoeck and Ruprecht, 2009) – the best modern bibliography of critical works on Handel.
Sadie, Stanley and Anthony Hicks (eds), Handel: Tercentenary Collection (Basingstoke: Macmillan, 1987) – a collection of essays by leading critics to commemorate the tercentenary of Handel’s birth.
Smith, Ruth, Handel's Oratorios and Eighteenth-Century Thought (Cambridge: Cambridge University Press, 1995) – the best guide to the political and ideological context for Handel’s English texts.
Steven LaRue, C., Handel and His Singers: The Creation of the Royal Academy Operas, 1720-1728 (Oxford: Clarendon Press, 1995) – a fascinating account of the first Royal Academy period, showing how Handel tailored individual opera productions for the voices at his disposal.