MAP20100104170 The Extra load index as a method for comparing the relative economy of load carriage systems / Ray Lloyd... [et al.] En: Ergonomics : the international journal of research and practice in human factors and ergonomics. - Oxon [United Kingdom] : Taylor & Francis, 2010- = ISSN 0014-0139. - 01/12/2010 Volumen 53 Número 12 - diciembre 2010 I. Lloyd, Ray . II. Title.