BibTeX is the most used bibliography processor in conjunction with LaTeX. To put bibliography styles in action, it uses a stack–based language written with postfixed notations. Recently, other approaches have been proposed: some use a programming language for designing bibliography styles, e.g., Perl in Bibulus; some are based on converters to xml TeXts and use xslt for bibliography styles; a recent proposal—the biblaTeX package—consists of using LaTeX command to control the layout of generated references… We propose a comparative study of these approaches and show which programming styles are encouraged, from a point of view related to methodology. Finally, we explain how this study has influenced the design of MlBibTeX, our multi–lingual reimplementation of BibTeX.