Bollinger, Edward E. On the Threshold of the Closed Empire: Mid-19th Century Missions in Okinawa. Pasadena, CA: William Carey Library, 1991. ISBN: 9780878082308. 
Former library book yet never loaned out and appears new apart from the standard library matter. Very good. Paperback.
"Baptist missionary-scholar Dr. Edward E. Bollinger has once again provided a rich interpretation of pioneering missionary endeavor in Ryukyu. Based on translated writings of the French Catholic missionary Fr. Theodore Forcade and Frs. Marnas and Leturdu, the story of the struggle of that Church to gain a foothold prior to the opening of Japan to the West is refreshingly told. Large sections of primary source material detail thos mid-19th century efforts and their results. A chapter on Protestant Pioneer Bettelheim and a comparison of his with early Catholic methods provides an additional dimension to the story." - Dr. Glen Ganno, American Baptist Mission, Tokyo, Japan.