ARACICH, Charles. 180 days of geography for fourth grade. Huntington Beach, California : Shell Education, [2018]. ©2018. 1 online zdroj (216 stran). Practice-assess-diagnose. Dostupné na internetu: <https://ebookcentral.proquest.com/lib/ujep-ebooks/reader.action?docID=5882500> ISBN 978-1-4258-5508-6.