Crediting Who's On First is recommended and linking back to the License is required. For example:
Data from Who's On First. License.
The Who's On First dataset is both an original work and a modification of existing open data. Some of those open data projects do require attribution. We have listed all sources in the full license file.
Remember, some sources require attribution, some do not. The format and structure that allows Who's On First to operate is made available under a Creative Commons Zero designation, and a shout out would be lovely.