Title The Economist quoted marketing professor Andrew Petersen about marketing on social networks in “Friends for sale.” (Sept. 17)  Body The Economist quoted marketing professor Andrew Petersen about marketing on social networks in “Friends for sale.” (Sept. 17) Expires   Sort Order 80  Attachments Created at 10/6/2009 4:18 PM  by Edwards Ellis, Laura  Last modified at 10/6/2009 4:18 PM  by Edwards Ellis, Laura  Use this page to add attachments to an item. Name