Roberts, J. W., & Huelbig, C. (1996). City kids & city critters!: Activities for urban explorers from the Houston Arboretum & Nature Center. Learning Triangle Press.
Cita Chicago (17th ed.)Roberts, Janet Wier, i Carole Huelbig. City Kids & City Critters!: Activities for Urban Explorers from the Houston Arboretum & Nature Center. New York, NY: Learning Triangle Press, 1996.
Cita MLA (8th ed.)Roberts, Janet Wier, i Carole Huelbig. City Kids & City Critters!: Activities for Urban Explorers from the Houston Arboretum & Nature Center. Learning Triangle Press, 1996.
Atenció: Aquestes cites poden no estar 100% correctes.