Article 18 [Cross-reference with articles 4, 5, 12, 13, 14] 1 The Parties shall endeavour to conclude, where necessary, bilateral and multilateral agreements with other States, in particular neighbouring States, in order to ensure the protection of persons belonging to the national minorities concerned. 2 - Where relevant, the Parties shall take measures to encourage transfrontier co-operation. education as a field of bilateral and regional co-operation the question of the official recognition of the diplomas by educational institutions of other States 37