17. Image attributions CC FlickR image by giant gingko CC FlickR image by jackdot101 CC FlickR image by Seattle Municipal Archives CC FlickR image by youngthousands CC FlickR image by KK+
18. CC FlickR image by City College Norwich CC FlickR image by isaaacbowen CC FlickR image by kraetzsche CC FLickR image by Vern Hart CC FlickR image by Runs with Scissors CC FlickR image by Urban Woodswalker