public void createTreeRoot(Node n) {
        Node root = n.getFirstChild();
        while(root != null) {
            if(root.getNodeType() == Node.ELEMENT_NODE) {
                ResearchItem rootItem = allResearch.get(root.getAttributes().item(0).getNodeValue());
                treeRoots.add(rootItem);
                Node child = root.getFirstChild();
                while(child != null) {
                    if(child.getNodeType() == Node.ELEMENT_NODE && child.getNodeName().equals("Item")) {
                        rootItem.addFollower(allResearch.get(child.getAttributes().item(0).getNodeValue()));
                        createTree(child);
                    }
                    child = child.getNextSibling();
                }
            }
            root = root.getNextSibling();
        }
    }