TY  - RPRT
TI  - Tracing selection effects in three non-probability samples.
AU  - Cas Barendregt
AU  - Agnes van der Poel
AU  - Dike van de Mheen
PY  - 2005
DO  - 10.1159/000085547
UR  - https://pubmed.ncbi.nlm.nih.gov/15990429/
ID  - 15990429
ER  -