https://support.google.com/admanager/thread/335847931/ask-faq-what-is-the-cheapest-day-to-buy-%F0%9D%99%8E%F0%9D%99%A5%F0%9D%99%9E%F0%9D%99%A7%F0%9D%99%9E%F0%9D%99%A9-%F0%9D%98%BC%F0%9D%99%9E%F0%9D%99%A7%F0%9D%99%A1%F0%9D%99%9E%F0%9D%99%A3%F0%9D%99%9A%F0%9D%99%A8-tickets https://support.google.com/admanager/thread/335850424?hl=en&sjid=17768375448123962051-NC https://support.google.com/admanager/thread/335849355/faq-what-days-are-flights-cheapest-for-%F0%9D%99%8E%F0%9D%99%A4%F0%9D%99%AA%F0%9D%99%A9%F0%9D%99%9D%F0%9D%99%AC%F0%9D%99%9A%F0%9D%99%A8%F0%9D%99%A9 https://support.google.com/admanager/thread/335852466/faq-rule-what-day-of-the-week-is-cheapest-for-amtrak