This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article provides insufficient context for those unfamiliar with the subject. Please help improve the article by providing more context for the reader. (February 2019) (Learn how and when to remove this message) This article relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources.Find sources: "Gall isographic projection" – news · newspapers · books · scholar · JSTOR (February 2019) The topic of this article may not meet Wikipedia's general notability guideline. Please help to demonstrate the notability of the topic by citing reliable secondary sources that are independent of the topic and provide significant coverage of it beyond a mere trivial mention. If notability cannot be shown, the article is likely to be merged, redirected, or deleted.Find sources: "Gall isographic projection" – news · newspapers · books · scholar · JSTOR (March 2019) (Learn how and when to remove this message) (Learn how and when to remove this message)