万能的虫友们，求助求助！

请问哪位朋友投过《Advances in Mechanical Engineering》，跪求解惑。我不久前投了一篇退修，但是编辑给返回的意见里要求获得相关引用成果的权限什么的，具体的我没太明白啥意思，具体具体内容如下：
Before submitting your revised manuscript, we would also be grateful if you could please ensure that you have obtained all necessary permissions for any material in your paper that has been previously published. Please e-mail copies of such permissions to the journal office when submitting the revised manuscript.

Please note, for legal reasons we would be unable to publish your paper in the journal should permissions not have been granted directly by the copyright holder for any previously published content, including figures and tables. Failure to provide all permissions at this stage may delay publication of your manuscript.
请问这是舍意思呢，是引用的所有文献都要经过作者授权才可以吗？怎样才能获得相关作者的授权呢~~
还有以后就到截止日期了，跪求指点迷津 返回小木虫查看更多