public BookData getByAuthor(String author){
		BookData subset = new BookData();
		
		//check each book in books
		for(int i=0; i<books.size(); i++){
			String temp = books.get(i).getAuthor();
			temp.trim().toLowerCase();
			author.trim().toLowerCase();
			//check if the author matches the given one
			if(temp.contains(author)){
				subset.addBook(books.get(i));
			}
		}
		//return any books by author
		return subset;
	}