Maintenance and repair Automobiles 19 Dwellings 12 Airplanes 9 Microcomputers 9 Equipment and supplies 6 Upgrading 6 Amateurs' manuals 4 Boats and boating 4 Electronic apparatus and appliances 4 Radar 4 Air conditioning 3 Design and construction 3 Electric equipment 3 Examinations, questions, etc 3 Handbooks, manuals, etc 3 Maintenance 3 Remodeling 3 Airlines 2 Amateur's manal 2 Aviation mechanics 2 Boatbuilding 2 Building 2 Buildings 2 Cellular telephones 2 Computers 2 Do-it-yourself work 2 Examinations 2 Gunsmithing 2 Management 2