Oppe, S. (1985). Contribution to evaluation of intermediate variables: Background paper. Institute for Road Safety Research SWOV, The Netherlands.
Chicago-referens (17:e uppl.)Oppe, Siem. Contribution to Evaluation of Intermediate Variables: Background Paper. Leidschendam: Institute for Road Safety Research SWOV, The Netherlands, 1985.
MLA-referens (9:e uppl.)Oppe, Siem. Contribution to Evaluation of Intermediate Variables: Background Paper. Institute for Road Safety Research SWOV, The Netherlands, 1985.
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