Sentence examples for both questionnaires have been from inspiring English sources

Both questionnaires have been validated [ 27- 29].

Both questionnaires have been widely employed in celiac disease.

Several translations of both questionnaires have been psychometrically validated previously in patients with GERD [ 30- 35].

Both questionnaires have been compared in one study where they showed a good correlation[ 13].

Both questionnaires have been validated for the Spanish population [ 37, 38].

The reliability and validity of both questionnaires have been previously examined [ 8, 14].

The final model included in both questionnaires has been defined through psychometric testing.

Both these questionnaires have been published previously [8].

Both the SPARK and the self-report questionnaires have been scanned using Teleform®.

Many self-completion HRQoL questionnaires have been developed and validated.

For example, questionnaires have been developed to sample people's thoughts after an upsetting event.