0001130464-08-000148 8-K 4 20080429 1.01 8.01 9.01 20080501 20080430 BLACK HILLS CORP /SD/ 0001130464 4911 460458824 SD 1231 8-K 34 001-31303 08791157 625 9TH STREET PO BOX 1400 RAPID CITY SD 57709 6057212343 625 9TH STREET PO BOX 1400 RAPID SD 57709 BLACK HILLS HOLDING CORP 20001222 8-K 1 form8k-ipp_sale.htm FORM 8K IPP SALE GRAPHIC 2 ballot.jpg GRAPHIC EX-10 3 ex-10.htm IPP PURCHASE AND SALE AGREEMENT EX-99 4 ex-99.htm IPP SALE NEWS RELEASE