@misc{Grygiel_Paweł_Testing,
 author={Grygiel, Paweł},
 howpublished={online},
 publisher={Educational Research Institute},
 language={pol},
 type={article},
 title={Testing the longitudinal invariance of the bifactor model using the example of The Perceived Peer Integration Questionnaire},
 keywords={sociology, longitudinal invariance, bifactor model, peer relationships, reliability, developmental changes},
}