Cita APA

(1980). The astronomical almanac for the year 1981: Data for astronomy, space sciences; geodesy surveying, navigation and other applications. U. S. Government Printing Office.

Citación estilo Chicago

The Astronomical Almanac for the Year 1981: Data for Astronomy, Space Sciences; Geodesy Surveying, Navigation and Other Applications. Washington: U. S. Government Printing Office, 1980.

Cita MLA

The Astronomical Almanac for the Year 1981: Data for Astronomy, Space Sciences; Geodesy Surveying, Navigation and Other Applications. U. S. Government Printing Office, 1980.