The Art of Writing About Art
A Short Guide to Writing About Art, 11th ed. (2015) by 
Writing About Art by 
Visual Methodologies: an introduction to researching with visual materials
Visual Literacy: Writing About Art by 
Understanding Art Objects: Thinking Through the Eye by 
Art Information : Research Methods and Resources by 
Principles of Art History Writing by Plagiarism is:
1. Claiming someone else's work (words and/or ideas) as your own.
2. An academic offense that can result in a lowered or even a failing grade, suspension, or--in severe cases--dismissal from the University.
3. Not a breach of law, but a profound breach of ethics.
4. Just plain DUMB, because properly acknowledging the sources undergirding your own work only improves your grade. There is no downside to doing the right thing, whereas the penalties for plagiarism can be severe and long-term.
Understand plagiarism and avoid it: