@article{Sae18a,
title = "Relational calculi in a deductive system",
journal = "Expert Systems with Applications",
volume = "97",
pages = "106 - 116",
year = "2018",
issn = "0957-4174",
doi = "https://doi.org/10.1016/j.eswa.2017.12.007",
url = "http://www.sciencedirect.com/science/article/pii/S0957417417308229",
author = "Fernando Sáenz-Pérez",
keywords = "Tuple relational calculus, Domain relational calculus, Relational algebra, SQL, Datalog, Database systems"
}