A 'Think Tank' is a a body of experts providing advice and ideas on specific political or economic problems. Most are non-profit organizations but some are supported by governments, advocacy groups, businesses, or independent funding agencies. A few think tanks offer consulting services, reports, lectures, experts in the field to promote their services and agendas.
Below are listed several of the more known think tanks. Some of the links below are to recent publications of the think tank while other links direct one to the general website. For those general website links make sure to search the site using "Brexit."
Center for European Policy Studies
European Council on Foreign Relations
European Parliamentary Research Service
Netherlands Institute of International Relations