APA (7th ed.) Citation

Velzeboer, P. T. (1971). Some comments on the economics of offshore mining. [publisher not identified].

Chicago Style (17th ed.) Citation

Velzeboer, P. Th. Some Comments on the Economics of Offshore Mining. [Delft, Th Netherlands?]: [publisher not identified], 1971.

MLA (9th ed.) Citation

Velzeboer, P. Th. Some Comments on the Economics of Offshore Mining. [publisher not identified], 1971.