An article titled"Research methods in Economics written by Tom Nunan and Susan Walker in 2014

I'm assuming that you want this in the form of Harvard Referencing.

[Author Surname], [Author Initial.] ([Year Published]) [Title].[Publication Title], [Volume number] ([Issue number]), [Pages Used].

All you have to do now is fill in the gaps:

Nuna, T and Walker, S. (2014). [Title].[Publication Title], [Volume number] ([Issue number]), [Pages Used].

Since, however, the title, publication title, volume number, issue number and the pages used are left out of the question, I have left these in brackets. If you know them, you can simply fill them in yourself, or tell me them and I will add them in.