The following books can all be found in Amazon - just click on the title link to go to Amazon. You may also want to see if your local public library has any of these titles by doing a search in worldcat.com.
Christianity Today, "Is the era of age segmentation over? A researcher argues that the future of youth ministry will require bringing the generations together. An interview with Kara Powell," Christianity Today, 2009, accessed January 15, 2018, http://www.christianitytoday.com/pastors/2009/summer/istheeraofagesegmentationover.html.
Ross, Christine, "Being an intergenerational congregation," Concordia University, Nebraska, Fall 2007, accessed January 15, 2018, http://www.cune.edu/resources/docs/Issues/fall2007/5article3.pdf.
Snailum, Brenda, "Intergenerational Ministry Beyond the Rhetoric," Fuller Youth Institute, April 4, 2011, accessed January 15, 2018, https://fulleryouthinstitute.org/articles/intergenerational-ministry-beyond-the-rhetoric.