Authors do not endorse one functional form (paper's thesis is sensitivity of elasticities to form) but single out the Translog electricity estimates as more reasonable than the quadratic || 'Note, that the electricity estimates are more reasonable than the ones obtained using the quadratic.' (p.155/154 of journal, corpus)
Jungeilges, J. and C. A. Dahl (1986): “Implications of Functional Form on Estimates of Japanese Energy Elasticities.” In: Energy Decisions for the Future: Challenges and Opportunities (eds. Mitsuru Miyata and Kenichi Matsui). Proceeding of the Eighth Annual International Conference of the International Association of Energy Economists, Tokyo, pp. 140-158