Halsema, J. J. (1983). E.J. Halsema: Colonial engineer (II). E.J. Halsema: colonial engineer (II)..
Lua i Stíl Chicago (17ú heag.)Halsema, James J. "E.J. Halsema: Colonial Engineer (II)." E.J. Halsema: Colonial Engineer (II). 1983.
Lua MLA (9ú heag.)Halsema, James J. "E.J. Halsema: Colonial Engineer (II)." E.J. Halsema: Colonial Engineer (II)., 1983.
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