Beer, G. (2010). Technology innovation in underground construction (1a. ed.). CRC Press.
Lua i Stíl Chicago (17ú heag.)Beer, Gernot. Technology Innovation in Underground Construction. 1a. ed. Boca Ratón: CRC Press, 2010.
Lua MLA (9ú heag.)Beer, Gernot. Technology Innovation in Underground Construction. 1a. ed. CRC Press, 2010.
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