Equipment and supplies Standards 69 Congresses 32 Design and construction 28 Food service 24 Sound 21 Catalogs 19 Radio 19 Telecommunication 19 Recording and reproducing 18 Maintenance and repair 16 Farm equipment 14 Heating 14 Acoustical engineering 13 Electric apparatus and appliances 13 Safety measures 13 Air conditioning 12 Testing 12 Chemical plants 11 Television 11 Handbooks, manuals, etc 10 Laboratories 10 Playgrounds 10 Purification 10 Petroleum industry and trade 9 Directories 8 Handicraft 8 History 8 Periodicals 8 Caterers and catering 7