http://all-free-download.com/free-icon/icons-sets/24x24_free_application_icons_icons_pack_120732.html
http://www.small-icons.com/packs/24x24-free-application-icons.htm

dropdown.png from https://creazilla.com/nodes/3251020-dropdown-menu-icon
Icons starting with 'Eclipse' are taken from Eclipse.
Icons starting with 'OTS' are our own production.