On the spectra of noncommutative 2D harmonic oscillatorJian Jing, Shi-Hua Zhao, Jian-Feng Chen and Zheng-Wen LongEur. Phys. J. C, 54 4 (2008) 685-690DOI: https://doi.org/10.1140/epjc/s10052-008-0560-3