APA

Kummer H., . (1968). Polishing of road stones on a drum apparatus. University Park, PA: Pennsylvania State University. Department of Highways. Joint Road Friction Program. Report no 17.

Chicago

Kummer HW, . 1968. Polishing of road stones on a drum apparatus. University Park, PA: Pennsylvania State University. Department of Highways. Joint Road Friction Program. Report no 17.

Harvard

Kummer H., . (1968). Polishing of road stones on a drum apparatus. University Park, PA: Pennsylvania State University. Department of Highways. Joint Road Friction Program. Report no 17.

MLA

Kummer HW, . Polishing of road stones on a drum apparatus. University Park, PA: Pennsylvania State University. Department of Highways. Joint Road Friction Program. Report no 17. 1968.