The set of playing card SVG images located in the /img/playing_cards/ directory was sourced from the following website:
<https://www.tekeye.uk/playing_cards/svg-playing-cards>
These images are licensed under the public domain, and the resources were created by <dan@tekeye.uk>.

The /img/flip_icon.svg icon was sourced from <https://freesvgicons.com>, specifically, it belongs to the Streamline pack <https://freesvgicons.com/packs/streamline>.
This icon is licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/deed.en).