Quiero implementar un árbol AVL en Java, esto es lo que tengo hasta ahora:

public class AVLNode {

  private int size; /** The size of the tree. */

  private int height; /** The height of the tree. */

  private Object key;/** The key of the current node. */

  private Object data;/** The data of the current node. */

  private Comparator comp;/** The {@link Comparator} used by the node. */

  /* All the nodes pointed by the current node.*/
  private AVLNode left,right,parent,succ,pred;

  /* Instantiates a new AVL node.
  *
  *  @param key the key of the node
  *  @param data the data that the node should keep
  *  @param comp the comparator to be used in the tree
  */
  public AVLNode(Object key, Object data, Comparator comp) {
    this(key,data,comp,null);
  }

  /* Instantiates a new AVL node.
  *
  * @param key the key of the node
  * @param data the data that the node should keep
  * @param comp the comparator to be used in the tree
  * @param parent the parent of the created node
  */
  public AVLNode(Object key, Object data, Comparator comp, AVLNode parent) {
    this.data = data;
    this.key = key;
    this.comp = comp;
    this.parent = parent;

    this.left = null;
    this.right = null;
    this.succ = null;
    this.pred = null;

    this.size = 1;
    this.height = 0;
 }

 /* Adds the given data to the tree.
 *
 * @param key the key
 * @param data the data
 * @return the root of the tree after insertion and rotations
 * @author <b>students</b>
 */
  public AVLNode add(Object key,Object data) {
    return null;
  }

  /* Removes a Node which key is equal 
  * (by {@link Comparator}) to the given argument.
  *
  * @param key the key
  * @return the root after deletion and rotations
  * @author <b>students</b>
  */
  public AVLNode remove(Object key) {
    return null;    
  }

Necesito implementar las funciones de agregar y quitar. Esto es lo que tengo hasta ahora, ambos deberían ejecutarse enO(log(n)) hora. Ambos deberían devolver la raíz de todo el árbol:

/*  Adds a new Node into the tree.
* @param key the key of the new node
* @param data the data of the new node
*/
public void add(Object key,Object data){
    if (isEmpty()){
        this.root = new AVLNode(key,data,comp);
    }
    else{
        root = this.root.add(key,data);         
    }
}

/**
 * Removes a node n from the tree where 
 * n.key is equal (by {@link Comparator}) to the given key.
 *
 * @param key the key
 */
public void remove(Object key){
    if (isEmpty()){
        return; 
    }
    else
        root = this.root.remove(key);
}

Necesito ayuda para hacer las funciones de agregar y quitar.

Existe alguna guía para describir cómo funcionan las operaciones de agregar y quitar? ¿Una biblioteca para copiar o algo donde pueda averiguar cómo / por qué funcionan los árboles AVL?