A web application freely available from [www.colorbrewer.org www.colorbrewer.org] published under the following license. I have adopted an 'Apache license' for ColorBrewer and its color schemes, on the initial advice of Frank Hardisty. Alan Isaac recommended updating to Version 2.0 for compatiblity with GPL licenses. Thanks Frank and Alan.

Here is the license:

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

This text from my earlier Apache License Version 1.1 also remains in place for guidance on attribution and permissions: Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions as source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. The end-user documentation included with the redistribution, if any, must include the following acknowledgment: "This product includes color specifications and designs developed by Cynthia Brewer (http://colorbrewer.org/)." Alternately, this acknowledgment may appear in the software itself, if and wherever such third-party acknowledgments normally appear. 4. The name "ColorBrewer" must not be used to endorse or promote products derived from this software without prior written permission. For written permission, please contact Cynthia Brewer at cbrewer@psu.edu. 5. Products derived from this software may not be called "ColorBrewer", nor may "ColorBrewer" appear in their name, without prior written permission of Cynthia Brewer.

This work must have the lavish citation ... Wording depends on context and I'm not too picky. If you add a note in the corner of a map, how about one of these:

   - Colors from www.ColorBrewer.org by Cynthia A. Brewer, Geography, Pennsylvania State University.
   - Map colors based on www.ColorBrewer.org, by Cynthia A. Brewer, Penn State.
   - Color symbols: ColorBrewer.org

A reference in a journal article or report might look like:

Uploaded by User:ClemRutter

Screen generated by ColorBrewer (v2 .0)

The original ColorBrewer (v1.0) was funded by the NSF Digital Government program during 2001-02, and was designed at the GeoVISTA Center at Penn State (National Science Foundation Grant No. 9983451, 9983459, 9983461).

The design and rebuilding of this new version (v2.0) was donated by Axis Maps LLC, winter 2009 and updated in 2013.

Cynthia Brewer: Concept / Colors / Editor

Mark Harrower: Design / User Interface

Ben Sheesley: Design / User Interface

Andy Woodruff: Developer

David Heyman: Developer