Wu Hong-Peng, Dong Lei, Zheng Hua-Dan, Liu Yan-Yan, Ma Wei-Guang, Zhang Lei, Wang Wu-Yi, Zhu Qing-Ke, Yin Wang-Bao, Jia Suo-Tang. Purity analysis of helium using quartz-enhanced photoacoustic spectroscopy with two non-resonant micro-tubesJ. Acta Physica Sinica, 2013, 62(7): 070701. DOI: 10.7498/aps.62.070701