The data and software displayed in the NAPROC-13 database are freely available with the following conditions:

• No license is needed for academic, nonprofit, and personal use.
• NAPROC-13 is the result of a large collaborative effort among several individuals at the University of Salamanca and at research institutions around the world. In order to acknowledge the scientists and engineers who have contributed to the USAL NAPROC-13 database and its data, and the organizations who have made this project possible through their generous funding, please cite the following reference:

José Luis López-Pérez, Roberto Therón, Esther del Olmo, David Díaz: NAPROC-13: a database for the dereplication of natural product mixtures in bioassay-guided protocols. Bioinformatics 23(23): 3256-3257 (2007)