<http://en.wikipedia.org/wiki/Binary_tree>
<http://en.wikipedia.org/wiki/Binary_search_tree>

Within the tree, each node has a value and a link set, since you say you want
to be link-based.  I don't really think "linked list" applies; you are talking
about a "linked tree".

Here's an example implementation that permits only one node with a given value
in a tree:

<sscce>
package testit;
public class Node <T extends Comparable <? super T>>
   implements Comparable <Node <T>>
{
  private final T value;
  private Node <T> left, right; // the links

  public Node( final T v )
  {
    this.value = v;
  }

  public final T getValue()
  { return value; }

  public final Node <T> getLeft()
  { return left; }
  public final void setLeft( Node <T> v )
  { left = v; }

  public final Node <T> getRight()
  { return right; }
  public final void setRight( Node <T> v )
  { right = v; }

  public int compareTo( Node <T> o )
  {
    return (this == o? 0
        : o == null? 1
        : value == null? (o.value == null? 0 : -1)
        : o.value == null? 1 /* guarantee symmetry */
        : value.compareTo( o.value ));
  }

  @Override public boolean equals( Object o )
  {
    try
    {
      return equals( getClass().cast(o) );
    }
    catch ( ClassCastException exc )
    {
      return false;
    }
  }

  public boolean equals( Node <T> o )
  {
    return (this == o || (o != null
       && (value == null? o.value == null : value.equals( o.value ))
       ));
  }

  @Override public int hashCode()
  {
    return (value == null? 0 : value.hashCode());
  }

  @Override public String toString()
  {
    return value.toString();
  }
}
</sscce>

<http://www.nist.gov/dads/HTML/properBinaryTree.html>