General Information on Unitron Refractors
General Correspondence – 1956 (Courtesy of Jon Miles): 
General Correspondence – 1966 (Courtesy of Tom Brennan): 
General Correspondence – 1967 (Courtesy of Tom Brennan): 
General Correspondence – 1968 (Courtesy of Tom Brennan): 
General Correspondence: 1981 (Indicates date of introduction of chrome setting circles):
Nihon Seiko Letterhead – 1983 (Courtesy of Stephen Brennan):
Polarex – Unitron Specification Sheets (Courtesy of Stephen Brennan):
Trademark Documentation: Unitron Trademarks
Technical Reports on Eyepiece Solar Filters (Courtesy of Will Thornton):
Technical Letter from Nihon Seiko on Removal/Replacement of Objective Lens (Courtesy of Tore Engen): Letter from NS 1971
Unitron Telescope Newsletter (circa 1970, Courtesy of Donovan Brock): 
Japanese Advertisement including several for ED/APO Refractors: 
