Helburn, S. W. (1971). Preparing to Teach Economics: Sources and Approaches. Interpretive Series Number 2.
Citazione stile Chigago Style (17a edizione)Helburn, Suzanne Wiggins. Preparing to Teach Economics: Sources and Approaches. Interpretive Series Number 2. 1971.
Citatione MLA (9a ed.)Helburn, Suzanne Wiggins. Preparing to Teach Economics: Sources and Approaches. Interpretive Series Number 2. 1971.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.