APA (7th ed.) Citation

Halim, S., Halim, F., & Effendy, S. (2020). Competitive programming 4: The lower bound of programming contests in the 2020s. Ingram content group.

Chicago Style (17th ed.) Citation

Halim, Steven, Felix Halim, and Suhendry Effendy. Competitive Programming 4: The Lower Bound of Programming Contests in the 2020s. United States, UK: Ingram content group, 2020.

MLA (8th ed.) Citation

Halim, Steven, et al. Competitive Programming 4: The Lower Bound of Programming Contests in the 2020s. Ingram content group, 2020.