I do if I am quoting specific numbers or quotes. I will also provide backlinks when appropriate. Often I just name the Source and let people look it up for themselves. Often, a source you use will provide many bits of information, that are not all in a row. Therefore, providing a link is useless. Naming the source, without the link, will allow the readers the opportunity to check it out. For instance, if I am quoting a federal statute, I will give the link to the proper citation. If I am just talking about federal law, I might just say multiple editions of the federal register or whatever.