The copyright law applies to copying properties that are copyrighted. If a book or an article in a magazine is copyrighted, they can be cited without written or oral permission. The person who cites should give credit to the source. Even parts of a book or a complete article can be copied, if it is for personal use. If that is done for distribution or for sale, then it is in violation of the copyright law. In such instances, we should get the permission from the source to do so.
When it comes to computer programs, disks, etc., the copyright prohibits the reproduction even for personal use.
Citing scriptures do not come under the copyright law. Usually, only parts are cited with references to its original human author. In certain cases, we also give credit to the translation.
There are certain things I have copyrighted and it is for legal purpose. Once, Shri Lanka asked for permission to use my training manuals. When I quoted my terms, including the fees, they balked off. They want it free. When it comes to scriptural things, there is certain freedom to be enjoyed, in Christ.
We should not violate the laws of the land.