3D spectacles; abacuses; accelerometers; accumulators, electric; acid hydrometers; acidimeters for batteries; acoustic alarms; acoustic conduits; acoustic couplers; actinometers; adding machines; aerials; aerometers; air analysis apparatus; alarm bells, electric; alarms; alcoholmeters; alidades; altimeters; ammeters; amplifiers; amplifying tubes; anemometers; animated cartoons; anode batteries; anodes; answering machines; anticathodes; anti-dazzle shades; anti-glare glasses; anti-interference...