HEISE, Marcus. Ballpoint Pens as Incentives with Mail Questionnaires – Results of a Survey Experiment. methods, data, analyses, [S. l.], v. 10, n. 1, p. 25–46, 2016. DOI: 10.12758/mda.2016.002. Disponível em: https://majournals.bib.uni-mannheim.de/mda/article/view/2016.002. Acesso em: 3 jul. 2026.