I'm considering titles for my book, and every time I think of a title, I do an internet search to see if the title has already been taken. One of the titles "Hack, Hack. Who's there?" is not taken by any book known to Google; however, this is the title of a talk given at a conference on internet security earlier this year. So, the main question: would there be any legal problem in using this title? A secondary question: would the title, even if being legal, be advisable because it could get mixed up with this talk?