BBL files are plain text files that are used by BibTeX. BibTeX is a program that is commonly used to generate bibliographies. The BBL file contains references defined in the LaTeX typesetting language. BBL files may be created manually or generated automatically by BibTeX from a corresponding .BIB file. BBL files are commonly used to cite references in a LaTeX document. BBL files are also often used by academic journals and other white paper authors to store bibliographic information.