Trying to install fonts on Linux Mint Lisa, but it looks like I have a permissions or ownership problem

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http://unix.stackexchange.com – I downloaded the Source Code Pro family of fonts, but cannot install them via the Font Viewer. If I give myself admin powers, I can manually add them to the rest of the fonts, so I'm guessing it's a permission issue. What would I need to do to install them via the Font Viewer? As a slight aside, I also read something about making sure the fonts were in the font cache as well. Is that necessary? If so, what's that entail? (HowTos)