The short answer is no, but there may be a couple of circumstances where it may be possible.
- The articles are public domain
- You have permission
The articles will say on them if they are public domain if they do not, assume they are copyrighted and that you will need permission from the person who wrote it.
Bear in mind that Amazon does not accept public domain works in their KDP program.
Whenever possible contact the writer and ask them if you can use their hard work in your ebook. If you can’t get hold of them assume their work is off-limits. They may ask for some financial compensation.
You can outsource and pay ghost writers for content. Try elance, fiverr or other online freelance websites.