Stories like the Tarzan series?

As a fan of Edgar Rice Burroughs work I have read a good portion of his books my personal favorite being Tarzan. I know that there have been countless ripoffs like Bomba the jungle boy but I can not seem to find any actual stories/authors. If someone could point me to a particular story/series id be appreciative Id also like to know where I might be able to find said works preferably to read online since they are most likely very old and out of print.