Nonlinear optical rectification in asymmetric double triangular quantum wells B. Chen, K.-X. Guo, R.-Z. Wang, Y.-B. Zheng and B. Li Eur. Phys. J. B, 66 2 (2008) 227-233 Published online: 30 October 2008 DOI: 10.1140/epjb/e2008-00398-y