21. Radio direction finding chart. 26DF. Radio direction finding aeronautical chart, lat. 25°-39°, long. 76°-90°. Scale 25 m.=0.8 in., scale 1:2,000,000. Bookmark Corporate/Agency Authors: Coast and Geodetic Survey and Commerce Dept. Publisher: Coast and Geodetic Survey Date: Oct. 13, 1949 SuDoc number: C 4.9/5:(no.&date)