APA Style

Halim, S. et al (2020). Competitive Programming 4: The Lower Bound of Programming Contests in the 2020s (Book 2: Chapters 5–9) (1). : LuLu.

MLA Style

Halim, Steven. et al. "Competitive Programming 4: The Lower Bound of Programming Contests in the 2020s (Book 2: Chapters 5–9)". 1 : LuLu, 2020. Text.