The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe - Rouzbeh Allahverdi; Mustafa A. Amin; Asher Berlin; Nicholas Bernal; Christian T. Byrnes; M. Sten Delos; Adrienne L. Erickcek; Miguel Escudero; Daniel G. Figueroa; Katherine Freese; Tomohiro Harada; Dan Hooper; et al. (The Open Journal of Astrophysics, 2021)