http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Some Calculations of ray paths in the ionosphere
FORSGREN, Sven K.H.: -- Some Calculations of ray paths in the ionosphere. 1951. -- (Reports from the Research Laboratory of Electronics.17.) -- (Transactions of Chalmers University of Technology,Gothenburg.104.= Elektroteknik,2o.) -- 1960:481 d. -- KB/Ho..
Reports from the Research Laboratory of Electronics 17