PT  - JOURNAL ARTICLE
AU  - Enriqueta Vallejo-Yagüe
AU  - Edward C Keystone
AU  - Sreemanjari Kandhasamy
AU  - Raphael Micheroli
AU  - Axel Finckh
AU  - Andrea Michelle Burden
TI  - Primary and secondary non-response: in need of operational definitions in observational studies
AID  - 10.1136/annrheumdis-2021-220202
DP  - 2021 Aug 01
TA  - Annals of the Rheumatic Diseases
PG  - 961--964
VI  - 80
IP  - 8
4099  - http://ard.bmj.com/content/80/8/961.short
4100  - http://ard.bmj.com/content/80/8/961.full
SO  - Ann Rheum Dis2021 Aug 01; 80