Here are some links that you can refer to for more information on the relative topics of this chapter:
- Historical details about how SQL was created: http://www.contrib.andrew.cmu.edu/~shadow/sql/sql1992.txt
- Handling NULL values: https://codeburst.io/understanding-null-undefined-and-nan-b603cb74b44c
- Handling duplicate values with pandas: https://www.python-course.eu/dealing_with_NaN_in_python.php
- About SQLite databases: https://www.sqlite.org/about.html
- Data modeling techniques: https://www.kimballgroup.com/data-warehouse-business-intelligence-resources/kimball-techniques/dimensional-modeling-techniques/
- pandas DataFrame functions: https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.html
