TY - JOUR T1 - The National Physical Laboratory JF - British Journal of Ophthalmology JO - Br J Ophthalmol SP - 441 LP - 442 DO - 10.1136/bjo.10.8.441 VL - 10 IS - 8 A2 - , Y1 - 1926/08/01 UR - http://bjo.bmj.com/content/10/8/441.abstract N2 - 300 Multiple ChoicesThis is a pdf-only article and there is no markup to show you.full-text.pdf ER -