* feat(route): add NBER working papers
* Modify the documentation
* Fix 'url is not defined' bug
* Remove async of get_element function
* Remove meaningless comments
* Update docs/en/journal.md
* Update docs/en/journal.md
* Change data acquisition methods to call api
* Remove wrong param 'ctx'
* Change documentation and radar
* Combine to file together & Cache each item & Add doi & Add pdf download link in description & Styling the description
* Add await in async function
* Clean the code
* Add config.cache.expire
* fix: typo
* Change 'abstract' acquisition method to parsing html from calling api
* Update lib/v2/nber/radar.js
* docs: fix typos
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DIYgod
Hengyu