I just did research, found them on their websites and emailed whatever public address I could find. Be direct, these are busy people so they dont want to read your life story when you are just asking them to review. Also, be ready to share your application - even go so far as giving them a sharing link to a Google doc with your questions and answers in it. If they have to say 'sure, I will take a look' and then wait for you to respond you may miss the window.