CSP - Content Security Policy
https://security.googleblog.com/2016/09/reshaping-web-defenses-with-strict.html
(CSP evaluator: https://csp-evaluator.withgoogle.com/)
https://scotthelme.co.uk/csp-cheat-sheet/
http://www.html5rocks.com/en/tutorials/security/content-security-policy/?redirect_from_locale=it
http://stackoverflow.com/questions/32893113/how-to-use-content-security-policy-with-social-media-buttons-widgets
(CSP evaluator: https://csp-evaluator.withgoogle.com/)
https://scotthelme.co.uk/csp-cheat-sheet/
http://www.html5rocks.com/en/tutorials/security/content-security-policy/?redirect_from_locale=it
http://stackoverflow.com/questions/32893113/how-to-use-content-security-policy-with-social-media-buttons-widgets