Literature 3: Zeng Zhijiang, Wei Li. Study on shape, content and concentration of plant pollen in honey. The 11th National Conference on the Development and Utilization of Pollen Resources. Fuyang city， Zhejiang province, China. 2010-08-01,pp: 197-202. Literature in Chinese, download from: 蜂蜜中植物花粉形态、含量及浓度研究 - 中国知网
