A unital casing structure of a portable electronic appliance such as a handheld or desktop calculator, comprising at least two panel sections having a straight boundary line therebetween and integrally coupled together across the boundary line whereby the panel sections are foldable with respect to each...http://www.google.fr/patents/US4703160?utm_source=gb-gplus-shareBrevet US4703160 - Casing structure of portable electronic appliance
