https://thejournalofheadacheandpain.biomedcentral.com/articles/10.1186/s10194-020-01213-3
https://thejournalofheadacheandpain.biomedcentral.com/articles/10.1186/s10194-020-01211-5
https://thejournalofheadacheandpain.biomedcentral.com/articles/10.1186/s10194-020-01212-4
https://thejournalofheadacheandpain.biomedcentral.com/articles/10.1186/s10194-020-01210-6
https://thejournalofheadacheandpain.biomedcentral.com/articles/10.1186/s10194-020-01214-2