Milligan, G., & Norris, P. (1990). Pipe jacking research results and recommendations. London: Pipe Jacking Association.
Παραπομπή Chicago StyleMilligan, George, and Paul Norris. Pipe Jacking Research Results and Recommendations. London: Pipe Jacking Association, 1990.
Παραπομπή MLAMilligan, George, and Paul Norris. Pipe Jacking Research Results and Recommendations. London: Pipe Jacking Association, 1990.
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