- s10831-013-9112-4.pdf
  - src: https://link.springer.com/article/10.1007/s10831-013-9112-4

- ntnulib_ja_L0801_0024_181.pdf 
    - src: http://api.lib.ntnu.edu.tw:8080/server/api/core/bitstreams/ae101510-30fa-4e80-a1a6-24bfdbf05087/content

