Vinal, William Gould. "PART II: NATURE-STUDY IN SCHOOLS". Nature Guiding, Ithaca, NY: Cornell University Press, 2019, pp. 167-350. https://doi.org/10.7591/9781501740862-005
Vinal, W. (2019). PART II: NATURE-STUDY IN SCHOOLS. In Nature Guiding (pp. 167-350). Ithaca, NY: Cornell University Press. https://doi.org/10.7591/9781501740862-005
Vinal, William Gould. "PART II: NATURE-STUDY IN SCHOOLS" In Nature Guiding, 167-350. Ithaca, NY: Cornell University Press, 2019. https://doi.org/10.7591/9781501740862-005