Connolly, Thomas M., and Carolyn E. Beg. Database Systems: A Practical Approach to Design, Implementation, and Management. Sixth edition. Harlow, Essex, England: Pearson, 2015. Web. <https://ebookcentral.proquest.com/lib/uea/detail.action?docID=5136720>.
Lans, Rick F. van der. Introduction to SQL: Mastering the Relational Database Language. 4th ed. Upper Saddle River, N.J.: Addison-Wesley, 2006. Web. <https://www.oreilly.com/library/view/introduction-to-sql/0321305965/?ar>.