Fangqing Gu Ziquan Liu Yiu-ming Cheung Hai-Lin Liu 0001 Optimization of Spectrum-Energy Efficiency in Heterogeneous Communication Network. 821-832 2017 SEAL https://doi.org/10.1007/978-3-319-68759-9_67 conf/seal/2017 db/conf/seal/seal2017.html#GuLCL17