Estimacie:
http://www.dcs.fmph.uniba.sk/~lukotka/PTS/17Management.pdf

Databazy:
https://www.youtube.com/watch?v=qI_g07C_Q5I
ORM examples
https://www.tutorialspoint.com/hibernate/hibernate_examples.htm
https://en.wikipedia.org/wiki/SQLAlchemy

Imutable data structures
Implementacia