public void merge(Node secondList) {
            if (first == null)
                return;

            if (secondList.first == null)
                return;

            Node thisNodeReference = this.first;
            Node secondNodeReference = secondList.first;
            Node thisNextNodeReference, secondNextNodeReference;

            while (thisNodeReference != null && secondNodeReference != null) {

                thisNextNodeReference = thisNodeReference.next;
                secondNextNodeReference = secondNodeReference.next;

                thisNodeReference.next = secondNextNodeReference;
                thisNodeReference = thisNodeReference.next;
                thisNodeReference.next = thisNextNodeReference;

                thisNodeReference = thisNextNodeReference;
                secondNodeReference = secondNextNodeReference;
            }
        }