"Sustantivos" are nouns in Spanish that are outlined in this colorful PowerPoint. Multiple examples and various rules for masculine, feminine, and plural nouns are provided. Lastly, there are six fill-in-the-blank sentences for students...

This site from the Indiana University provides a concise, but thorough, Spanish explanation of nouns that do not follow the normal rules for gender. Greek and latin influence is examined. Great review for advanced students or teachers...