Should I Cite Logos?
Logos can be protected by both copyright and trademark. This is entirely orthogonal to the issue of citation. By academic convention, you are required to cite any work which contributed intellectually to your work. If I base my work on a paper from the 1800s, I am still required to cite it, even though it is likely to be long out of copyright. This is not a legal requirement, but a question of academic ethics.

Whether you are required to cite these logos will depend on whether they make an intellectual contribution to your work, and the common practices of the field in which you are working. It does not depend on whether the logos are under copyright or trademark.