DBS: 3.6. Cost Of Operations (4): Heap File + Unclustered B+Tree Index 

This is the Database Systems II
Instructor: Ouldooz Baghban Karimi (ouldooz.com)
Textbook: Database Management Systems
Raghu Ramakrishnan, Johannes Gehrke
pages.cs.wisc.edu/~dbbook/
Database System Concepts
Avi Silberschatz, Henry F. Korth, S. Sudarshan
www.db-book.com/