I use the website Citation Machine whenever I need to write a bibliography, and I think awhile ago it became a site that could tell when you were using adblock extensions so it would ask you to turn off adblock. I haven’t used Citation Machine in a long time, so when I actually saw ads it was surprising. One thing I think they do is interesting with their ads is that to use the site ad free for 2 days, you have to deal with an interactive ad. Its funny how they don’t give you the option to just deal with the ads and you have to experience the interactive ad as well, because I did not click anything stating that I wanted to remove the ads at all.