In your list of sources of power, you include a negotiator's position in the organizational hierarchy. So a hard-nosed boss may be 'in charge' but may not be a sufficiently credible leader to inspire her subordinates to follow directions. Often people assume they have less power than other parties. You need to ask questions and listen very closely to the answers to find out whether that assumption is correct. It follows from item 3 that one of the most significant sources of power in negotiation is based on your capacity to listen, to gain information.
Information is the fundamental asset in negotiation.
Information comes into the ears. You do not learn by listening to yourself. We should use them in that ratio. Good luck with your negotiations.