Answer
$\color{blue}{ \sqrt[12]{m}}$
Work Step by Step
Use the rule $\sqrt[m]{\sqrt[n]{a}}=\sqrt[mn]{a},a \gt0$ to obtain:
$=\sqrt[4]{\sqrt[3]{m}}
\\=\sqrt[4(3)]{m}
\\=\color{blue}{ \sqrt[12]{m}}$
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