https://isc.sans.edu/diary/Use+of+XFrameOptions+and+CSP+frameancestors+security+headers+on+1+million+most+popular+domains/29698
Use of X-Frame-Options and CSP frame-ancestors security headers on 1 million most popular domains
Use of X-Frame-Options and CSP frame-ancestors security headers on 1 million most popular domains, Author: Jan Kopriva
most popular domainsframe optionssecurity headersusex