APA (7th ed.) Citation

International Astronomical Union. (1968). Proceedings of the ... colloquium of the International Astronomical Union.

Chicago Style (17th ed.) Citation

International Astronomical Union. Proceedings of the ... Colloquium of the International Astronomical Union. [Wechselnde Verlagsorte], 1968.

MLA (9th ed.) Citation

International Astronomical Union. Proceedings of the ... Colloquium of the International Astronomical Union. 1968.

Warning: These citations may not always be 100% accurate.