http://www.theverge.com/2015/5/4/8547433/microsoft-office-2016-real-time-co-authoring-features
http://www.theverge.com/2013/11/7/5075192/office-web-apps-real-time-editing-features
http://www.pcworld.com/article/2105861/one-year-later-microsoft-offices-collaboration-tools-are-still-a-work-in-progress.html
http://www.pcworld.com/article/2033437/collaboration-in-microsoft-office-painful-but-not-impossible.html
http://www.computerworld.com/article/2943496/enterprise-applications/microsofts-office-2016-preview-gets-realtime-editing-in-word-and-more.html