Willis, W. R. (1979). 200 years and still counting: Past, present and future of the sunday school. Victor Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रWillis, Wesley R. 200 Years and Still Counting: Past, Present and Future of the Sunday School. Illinois: Victor Books, 1979.
एमएलए (9वां संस्करण) प्रशस्ति पत्रWillis, Wesley R. 200 Years and Still Counting: Past, Present and Future of the Sunday School. Victor Books, 1979.
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