
Artists and writers own the copyright for anything they have created. They are protected by copyright law - this prevents other people from copying it without their permission.
Copyright law protects anything you can copy - whether it is images or text from books, magazines or the internet. You are allowed to copy images and text for your own private use as long as you do not plan to use it in your own artwork or make any money from it.
If you are including secondary sources in your work journal then that's fine - but do acknowledge where you got them from whereever possible.
If you are planning to use somebody else's work in your artwork, then you must get permission from whoever owns the copyright. The copyright details are usually included in books and magazines on the front page. For TV programmes you may need to contact the production company. Websites usually have copyright information at the bottom of the webpage. For example if you look at the bottom of the BBC Schools website there is a link that says Schools Copyright (bbc.co.uk/schools/copyright/).
Even if you do not need copyright permission, it is always good practice to acknowledge where your images or text come from. It shows the range of sources you have used.