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WikiPedia: Ibb http://www.britannica.com/EBchecked/topic/280558/I... http://www.smb-digital.de/eMuseumPlus?service=Exte... http://www.smb-digital.de/eMuseumPlus?service=Exte... //tools.wmflabs.org/geohack/geohack.php?language=v... https://books.google.com/books?id=C2a6eVpf_wIC&pg=... https://books.google.com/books?id=IxEuAQAAIAAJ https://books.google.com/books?id=YGjMQp2OQAgC&pg=... https://books.google.com/books?id=cjrRAAAAMAAJ https://books.google.com/books?id=nDsjyU2Re6AC&pg=... https://books.google.com/books?id=tjXRfqBv_0UC&pg=...