Citing for the first time

Hi, I was just wondering if anyone had any advice on how to cite/ what are acceptable sources for citing in an essay. I'm doing my EPQ on the oppression of the Catholics in Ireland at the hands of the English and have been using journals from JSTOR mostly. However, I have also found cartoons from Victorian magazines such as 'Punch'. Firstly are JSTOR sources appropriate to cite and does anyone know how to cite political cartoons?