Principles and methods of co-operation of agriculture in Bulgaria, by I. Ranchev.--Technical equipment of Bulgarian agriculture, by M. Maximova.-- Planning the activity of agricultural enterprises in Bulgaria, by V. Anachkov.- -Production funds at the co-operative farms, by D. Kinov.--Organization of work at Bulgarian co-operative farms, by M. Minkov.--Labour norms at co-operative farms, by I. Grozev.--Co-operative farm finances, by K. Zanev