On the spectra of noncommutative 2D harmonic oscillator Jian Jing, Shi-Hua Zhao, Jian-Feng Chen and Zheng-Wen Long Eur. Phys. J. C, 54 4 (2008) 685-690 Published online: 08 March 2008 DOI: 10.1140/epjc/s10052-008-0560-3