(c) medical and social assistance, the prevention of employment injuries, workmen's compensation, industrial hygiene and housing; (d) the right of association and freedom for all lawful trade union activities, and the right to conclude collective agreements with employers or employers' organisations. PART IV. VOCATIONAL TRAINING, HANDICRAFTS AND RURAL INDUSTRIES Article 16 Persons belonging to the populations concerned shall enjoy the same opportunities as other citizens in respect of vocational training facilities. Article 17 1. Whenever programmes of vocational training of general application do not meet the special needs of persons belonging to the populations concerned governments shall provide special training facilities for such persons. 2. These special training facilities shall be based on a careful study of the economic environment, stage of cultural development and practical needs of the various occupational groups among the said populations; they shall, in particular enable the persons concerned to receive the training necessary for occupations for which these populations have traditionally shown aptitude. 3. These special training facilities shall be provided only so long as the stage of cultural development of the populations concerned requires them; with the advance of the process of integration they shall be replaced by the facilities provided for other citizens. Article 18 1. Handicrafts and rural industries shall be encouraged as factors in the economic development of the populations concerned in a manner which will enable these populations to raise their standard of living and adjust themselves to modern methods of production and marketing. 2. Handicrafts and rural industries shall be developed in a manner which preserves the cultural heritage of these populations and improves their artistic values and particular modes of cultural expression. PART V. SOCIAL SECURITY AND HEALTH Article 19 Existing social security schemes shall be extended progressively, where practicable, to cover-(a) wage earners belonging to the populations concerned; (b) other persons belonging to these populations. Article 20 1. Governments shall assume the responsibility for providing adequate health services for the populations concerned. 2. The organisation of such services shall be based on systematic studies of the social, economic and cultural conditions of the populations concerned. 3. The development of such services shall be co-ordinated with general measures of social, economic and cultural development. PART VI. EDUCATION AND MEANS OF COMMUNICATION Article 21 Measures shall be taken to ensure that members of the populations concerned have the opportunity to acquire education at all levels on an equal footing with the rest of the national community.