Question: My novel is about a subject better covered by other authors. Can I lift some portion of their work and then give them credit in the acknowledgement page? What if I change it slightly- use different words for instance but keep their content intact? Does it matter if I don't try to sell my book- just give to my family and friends? Is there some concise source for this problem?Answer:
If you are writing non-fiction, you can certainly discuss ideas and information other authors have written about, giving proper credit regarding the source. Ideas cannot be copyrighted, only their expression. However, passing off someone else's research as your own without giving them credit is plagiarism and can invite a lawsuit by the other publisher. Don't just use a bibliography. Give credit in the actual text itself or via footnotes. You can use some quotations, if they are not too long, are clearly identified as quotations, and you give proper credit to their authors.
If this is a novel (fiction), there is no good reason to copy someone else's story. Yes, there are re-tellings of classic tales that are in public domain to make them accessible to a new generation. But don't copy from works not in the public domain. It's illegal and immoral.
Either make your story original or put away your pen and tell people to read the other person's novel.