The detailed analysis (in Chinese) of the source code of google's word2vec. I really appreciate this source code since it is simple and efficient. However, it is not easy to understand unless you know both the paper and c language quite well.
A Chinese blog is shown here: https://blog.csdn.net/jeryjeryjery/article/details/80245924
A PyTorch implementation of word2vec is here: https://github.com/liuwei1206/CNN_CBOW