|siderealday=4.144177 da<ref name=uranussatfact/><ref name=Britannica>Ingersoll, Andrew P. "[http://www.britannica.com/eb/article-9074205 Umbriel]." Encyclopædia Britannica. 2008. Encyclopædia Britannica Online. 14 June 2008.</ref>
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|siderealday=4.144177 da<ref name=uranussatfact/><ref name=Britannica>Ingersoll, Andrew P. "[https://www.britannica.com/eb/article-9074205 Umbriel]." Encyclopædia Britannica. 2008. Encyclopædia Britannica Online. 14 June 2008.</ref>