J. Hagan, “Letter to the Editor: A Randomized, Double-Blinded, Placebo-Controlled, Cross Over Study Evaluating the Efficacy and Safety of Timolol Ophthalmic Solution as an Acute Treatment of Migraine”, kjm, vol. 13, no. S2, pp. 29–30, Mar. 2021, doi: 10.17161/kjm.vol1315733.