When a unit of any work–book, audiobook, song, music video, and short or feature films sold.
Chidi Nwaogu on Books
Attribution
Quotes and notes from Wikiquote: Chidi Nwaogu (page history), available under CC BY-SA 4.0.
Quotes and notes from Wikiquote: Chidi Nwaogu (page history), available under CC BY-SA 4.0.