There are a huge amount of images that you are free to view on the WWW. However, images are covered by copyright and permission should be sought prior to using in assignments. Finding the original copyright owner can be a problem. The Library has databases where you can reproduce images. Check the information links for the requirements in reproducing images.
Also, there are many computer aided designs but often these designs are not accurate and they have been produced by university students for assignments. Look at the www site where these images are posted.
Finding Images in Library Databases - An online presentation with specific instructions on how to use ARTstor and the Oxford Art Online databases.
Below are many links to resources where you can locate images.
Complete exercise 7a from the worksheet