TY  - JOUR
A1  - Wendt, Heike
A2  - Schwippert, Knut
A3  - Gerick, Julia
A4  - Schulz-Heidorf, Katrin
TI  - It??s all about validity: Preparing TIMSS and PIRLS background questionnaires for the 21st century
JF  - Tertium Comparationis
SN  - 0947-9732
PY  - 2017
IS  - 1
SP  - 28
19
DO  - 10.xxx/TC1701028
UR  - https://content-select.com/index.php?id=bib_view&doi=10.xxx%2FTC1701028
PB  - Waxmann Verlag
CY  - 48159 Münster
RI  - 
ER  -