Sources:
www.marketingsherpa.com/article/case-study/clever-preshow-direct-mail-web
www.thetradeshownetwork.com/trade-show-blog/trade-shows-direct-mail-%E2%80%93-a-winning-combination
www.handshake.com/blog/trade-show-marketing-show/
american-image.com/trade-show-marketing-is-direct-mail-dead/
www.ruthstevens.com/articles/how-to-triple-the-effectiveness-of-your-trade-show-marketing-program/
www.suttle-straus.com/blog/how-to-stand-out-at-your-next-trade-show-with-an-integrated-campaign