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.
Chicago Style (17. basım) AtıfDowling, J. W. F., Rudolfo Franco L., ve R. B. C. Russell. Natural Asphalts: Their Occurrence, Properties and Use in Road Construction in Columbia. Crowthorne, Berkshire: Transport and Road Research Laboratory, 1982.
MLA (9th ed.) AtıfDowling, 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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