It's been difficult over the years to get a clear picture of the complete catalogue of Villa-Lobos's music, but musico-bibliographers have been working behind the scenes to bring things into focus. The Museu Villa-Lobos began to clean things up with the publication in 1965 with the first edition of Villa-Lobos: Sua Obra. This was followed by the 2nd edition in 1972.
David P. Appleby became Villa's Köchel in 1988, with the publication of his 1988 book Heitor Villa-Lobos: a bio-bibliography. (Bio-bibliographies in music, no. 9. New York: Greenwood Press). Appleby came up with 567 numbers ("W" for Work, though these are often changed to "A" for Appleby, which is only right) for the major pieces Villa-Lobos wrote. There are certainly missing works in Appleby's listing, and he didn't include a fair number of choral and vocal works included in the Musica Sacra and Guia Pratico collections in the main listing. However, Appleby's list should reduce some of the hyperbole concerning Villa-Lobos's prodigious output (though there are lots of sources out there that continue to throw out 2,000 as a total).
Appleby's book was immediately followed in 1989 by the third edition of Villa-Lobos: Sua Obra, by the Museu Villa-Lobos. These two works have been my main guides in my Villa-Lobos web work so far.
download here. Thanks once more to the amazing Museu Villa-Lobos for their work in making the music of Villa-Lobos more accessible in the 21st Century.