Müller, Jörg M.; Achtergarde, Sandra; Winkel, Sandra; Frantzmann, Hanna; Steinberger, Kathrin; Skorozhenia, Olena; Beyer, Thomas; Fürniss, Tilman; Furniss, Tilman; Furniss, Tilman; Furniss, Tilman; Postert, Christian: Inter-rater reliability and aspects of validity of the parent-infant relationship global assessment scale (PIR-GAS)