On Tuesdays and Thursdays, Janet Ring can often be found in a back room of the Douglas County Library, searching through old editions of The News-Review on microfilm to find stories requested by patrons. Over the years, she has looked up everything from obituaries to 1920s murder cases. Ring is one of the longest-serving of the 50 volunteers who help make the Roseburg branch run. She received a certificate Thursday morning honoring her 30 years of service. Ring, 56, of Green began volunteering when the library was in the Douglas County Courthouse annex. She saw a sign recruiting volunteers to …