ทิศ

Going From Point "A" to "B" http://geology.isu.edu/geostac/Field_Exercise/topomaps/a_to_b.htm

Get a Bearing http://geology.isu.edu/geostac/Field_Exercise/topomaps/bearing.htm

Finding Your Way with Map and Compass http://egsc.usgs.gov/isb/pubs/factsheets/fs03501.html

หลักการคำนวณวงรอบ http://www.cte.kmutt.ac.th:8080/WebProjectProduct/Traverse/pagecontent/Calculator/Open%20traverse/Open2/PAGE%20OPEN2.htm
http://cyberlab.lh1.ku.ac.th/elearn/faculty/forest/fo26/501.htm

ทิศ http://www.map-reading.com/chap6.php