Online encyclopaedias are great for short, concise and correct information. Search by the key words black death or plague. Don't forget the ready made citations and read aloud facility.
Primary source materials are first-hand accounts typically produced at the time of the event. Examples might include artwork, plays, poems, songs, letters, journals and writings from that time period.
It is important that you show your teacher you used a variety of reliable resources. Use the online Reference Generator available through the Portal to create your citations. Make sure you alphabetically sort them afterwards.
A sample bibliography for 3 resources provided on this page would look like:
The Black Death n.d., Science Museum, accessed 4 May 2016, http://www.sciencemuseum.org.uk/broughttolife/themes/
Black Death 2016. Britannica School. Retrieved 4 May 2016, from http://school.eb.com.au/levels/middle/article/574643
Robson, P 1996, All About The Great Plague, MacDonald, Hove.