APA Style

Halim, S. et al (2018). Competitive Programming 4: The Lower Bound of Programming Contests in the 2020s (Book 1: Chapters 1–4) (1). : LuLu.

MLA Style

Halim, Steven. et al. "Competitive Programming 4: The Lower Bound of Programming Contests in the 2020s (Book 1: Chapters 1–4)". 1 : LuLu, 2018. Text.