1. A linear lower bound on the gonality of modular curves;Abramovich;Int. Math. Res. Not. IMRN,1996
2. Torsion points on elliptic curves and gonalities of modular curves;Derickx,2012
3. Reduktion algebraischer funktionenkörper nach primdivisoren des konstantenkörpers;Deuring;Math. Z.,1942
4. M. Derickx, M. van Hoeij, www.math.fsu.edu/~hoeij/files/X1N. Files: gonality (upper bounds with explicit functions gN, and an overview), Subfields (other sources of upper bounds) cusp_divisors (divisors of f2,f3,…), folder LowerBoundsGonality (Magma files for proving lower bounds), and folder OtherComputations (files for: Lemma 1, Proposition 6 (N=25) and Conjecture 1 (N⩽100)).
5. Curves with infinitely many points of fixed degree;Frey;Israel J. Math.,1994