APA (7th ed.) Citation

Cox, R., & Brna, P. (1994). Supporting the use of external representations in problem solving: The need for flexible learning environments.

Chicago Style (17th ed.) Citation

Cox, Richard, and Paul Brna. Supporting the Use of External Representations in Problem Solving: The Need for Flexible Learning Environments. Edinburgh, 1994.

MLA (9th ed.) Citation

Cox, Richard, and Paul Brna. Supporting the Use of External Representations in Problem Solving: The Need for Flexible Learning Environments. 1994.