Recommendation
Common open source license option are summarized very nicely at http://choosealicense.com/licenses/
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How to apply this license
Create a text file (typically named LICENSE or LICENSE.txt) in the root of your source code and copy the text of the license into the file. Replace [yyyy] with the current year.
License Dependencies
In some cases, it may not be possible to release Harvard Library code under the recommended license. This can happen when the code includes other open source projects that have a more restrictive license that requires projects that incorporate it to inherit the license terms. For example, if a project uses open source code licensed under the LGPL or GPL licenses, there a requirements that the consuming project also be licensed in the same manner. One example is the FITS project. FITS bundles code release under the LGPL license, and is consequently also released under the LGPL license.
Embedded licenses
If a release propject includes other licensed code, the license.txt file should include a list of the file paths to all of the embedded license.txt files for subprojects within the main project