An enclave is a part of the territory of a state that is enclosed within the territory of another state. To distinguish the parts of a state entirely enclosed in a single other state, they are called true enclaves. A true enclave cannot be reached without passing through the territory of a single other state that surrounds it. "Vinokurov (2007)" calls this the restrictive definition of "enclave" given by international law, which thus "comprises only so-called 'true enclaves'". Two examples are Büsingen am Hochrhein, a true enclave of Germany, and Campione d'Italia, a true enclave of Italy, both of which are surrounded by Switzerland.