Zeitschrift 130 Engineering 77 Technology 70 Food 58 History 54 Pe ́riodiques 53 Biotechnology 51 Materials 47 Research 45 Historia 44 Hospitality industry 44 Management 40 Construcción 37 Electronics 37 Tecnología 37 Social aspects 36 Electrical engineering 35 Training of 35 Capacitación 34 Empleados 34 Employees 34 Manuales de formación 34 Training manuals 34 Environmental protection 33 Buildings 31 Civil engineering 31 Study and teaching 31 Tecnología de la información 30 Information technology in education 29 Industrial safety 28