These articles appear unchanged in the tenth edition (1903) but greatly extended versions, co-authored with Helmert, appear in the eleventh edition (1911) alongwith a new article on "Map" co-authored with Close.
These articles appear unchanged in the tenth edition (1903). Greatly extended versions, co-authored with Helmert, appear in the eleventh edition (1911) along with a new article on "Map" co-authored with Close.