heterogeneity and paid search effectiveness: A large scale field experiment." Econometrica, 83.1 (2015): 155-174. • Gordon, B. R., et al. "A comparison of approaches to advertising measurement: Evidence from big field experiments at Facebook. Whitepaper." (2018). • Gordon, Brett R., et al. "A comparison of approaches to advertising measurement: Evidence from big field experiments at Facebook." Marketing Science, 38.2 (2019): 193-225. • Fredreik, Jesse and Maurits Martijn " The new dot com bubble is here: itʼs called online advertising.” The Correspondent 6 Nov. 2019. https://thecorrespondent.com/100/the-new-dot-com-bubble-is- here-its-called-online-advertising/13228924500-22d5fd24