21117—if you have listed more reference sources than those u

than 后的 those 是为了避免重复而用来指代同类的 reference sources.把这个句子拆分改写为如下就清楚了：
You have listed reference sources 你已经列出一些参考源
You have listed the reference sources used in your essay, 你已经列出用于你的论文的参考源
If the former is more than the latter, your essay will be considered to be inveracious. 如果前者比后者更多一些,那么你的论文会被认为是不真实的.
1—if you have listed more reference sources than those used in your essay：理解为“如果你列出了更多的参考资源比那些用于你的论文”没有错误,但是为什么非要用英语式的句子说汉语呢!修改如下：
如果你列出了比用于你的论文中更多的参考源,…
be considered to：被认为是
inveraclous：单词写错了,应该是 inveracious