Dyfyniad APA

Dowling, J. W. F., Franco L., R., & Russell, R. B. C. (1982). Natural asphalts: Their occurrence, properties and use in road construction in Columbia. Transport and Road Research Laboratory.

Dyfyniad Arddull Chicago

Dowling, J. W. F., Rudolfo Franco L., and R. B. C. Russell. Natural Asphalts: Their Occurrence, Properties and Use in Road Construction in Columbia. Crowthorne, Berkshire: Transport and Road Research Laboratory, 1982.

Dyfyniad MLA

Dowling, J. W. F., et al. Natural Asphalts: Their Occurrence, Properties and Use in Road Construction in Columbia. Transport and Road Research Laboratory, 1982.

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