الإتاحة: https://methods.sagepub.com/video/researching-consumer-perspectives-on-sustainability-using-metaphor-elicitat
الإتاحة: https://sk.sagepub.com/video/creating-valid-and-reliable-survey-items
الإتاحة: https://sk.sagepub.com/video/niall-bolger-defines-longitudinal-survey