APA

British Standard nr 4692:1971, . (1971). Method for determination of softening point of bitumen (Ring and ball). London: British Standard nr 4692:1971.

Chicago

British Standard nr 4692:1971, . 1971. Method for determination of softening point of bitumen (Ring and ball). London: British Standard nr 4692:1971.

Harvard

British Standard nr 4692:1971, . (1971). Method for determination of softening point of bitumen (Ring and ball). London: British Standard nr 4692:1971.

MLA

British Standard nr 4692:1971, . Method for determination of softening point of bitumen (Ring and ball). London: British Standard nr 4692:1971. 1971.