References

Ballou, J., 2008. Open-ended question. Encycl. Surv. Res. Methods, 43: 548-550.

Good, C.V., 1973. Dictionary of Education. 3rd Edn., McGraw-Hill, New York.

Hylen, J., 2006. Open educational resources: Opportunities and challenges. Proc. Open Educ., 1: 49-63.

Littlejohn, A., I. Falconer and L. Mcgill, 2008. Characterising effective elearning resources. Comput. Educ., 50: 757-771.
Direct Link  |  

Sauro, J., 2011. Measuring usability with the System Usability Scale (SUS). USA. http://www.measuringu.com/sus.

Shneiderman, B. and C. Plaisant, 2004. Designing the User Interface: Strategies for Effective Human-Computer Interaction. 4th Edn., Addison-Wesley Professional, Boston, USA., ISBN-13: 978-0321197863, Pages: 652.