Vdovjak, R. ., F. . Frasincar, G. . Houben, and . P. . Barna. “Engineering Semantic Web Information Systems in Hera”. Journal of Web Engineering, vol. 2, no. 1-2, Jan. 2004, pp. 003-26, https://journals.riverpublishers.com/index.php/JWE/article/view/4373.