Citations in papers are very important in order to show the sources of your information, its relevance and timeliness, but above all, it is a standardized way of giving credit to the original authors of the information used in your paper so that, first of all, they can earn their due credit, but, secondly, to avoid plagiarism, which is, in rough terms, passing other´s research or ideas as your own without giving them credit.
The old man believed that he must watch over the cat, the goats and the pigeons in San Carlos. The man was not able to fulfill his responsibilities so was guilty and wondered what would the animals do in his absence