The Carl Nielsen Edition presents a collected, critical edition of Nielsen's works in 32 volumes plus study scores and parts. Each volume has an introduction, describing the history of the work and a critical report containing a survey of the sources and a list of all emendations and variants.
All volumes are bilingual (Danish/English); the operas and large choral works, furthermore, will be available in two versions: Danish/English and Danish /German.
Works included in volumes with more than one work are available in separate cloth-bound editions.
The works are available for download here, as well as the prefaces and descriptions of sources.
In addition to the edition of the music, Nielsen's collected writings have been published:
Carl Nielsen til sin samtid, vols. 1-3, published by John Fellow. Copenhagen 1999.
Articles about Carl Nielsen's music can be found in Carl Nielsen Studies, and an edition of his letters is forthcoming.