Except as otherwise specifically provided herein, the power-of-attorney granted herein shall not in any manner revoke in whole or in part any power-of-attorney that each person whose signature appears below has previously executed. This power-of-attorney shall not be revoked by any subsequent power-of-attorney each person whose signature appears below may execute, unless such subsequent power specifically refers to this power-of-attorney or specifically states that the instrument is intended to revoke all prior general powers-of-attorney or all prior powers-of-attorney.