"Each true story in this series by outstanding authors Janet and Geoff Benge is loved by adults and children alike. More Christian Heroes: Then & Now biographies and unit study curriculum guides are coming soon. Fifty-five books are planned, and thousands of families have started their collections! World War II veteran Betty Greene's desire to use airplanes to help spread the gospel was realized when she helped found the Mission Aviation Fellowship (MAF) (1920-1997).