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Helmer, Loreine M.L., Roxane A.F Weijenberg, Ralph de Vries, Wilco P. Achterberg, Stefan Lautenbacher, Elizabeth L. Sampson, and Frank Lobbezoo. "Crying Out in Pain—A Systematic Review Into the Validity of Vocalization As an Indicator for Pain." Eur J Pain 2020.

Helmer, Loreine M.L., et al. "Crying Out in Pain—A Systematic Review Into the Validity of Vocalization As an Indicator for Pain." Eur J Pain 2020.