Condensed Statements of Cash Flows (USD $)	9 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Cash flows from operating activities
Royalties received	$ 25,004,610	$ 9,006,698
Interest received	1,269	4,597
Expenses paid	(867,455)	(706,064)
Net cash provided by operating activities	24,138,424	8,305,231
Cash flows from investing activities
Maturities of U.S. Government Securities	35,000	489,000
Purchases of U.S. Government Securities	(205,054)	(373,332)
Net cash provided by (used for) investing activities	(170,054)	115,668
Cash flows used for financing activities
Distributions to Unitholders	(19,220,815)	(17,056,013)
Net change in cash and cash equivalents	4,747,555	(8,635,114)
Cash and cash equivalents, beginning of year	10,253,474	8,693,691
Cash and cash equivalents, end of period	15,001,029	58,577
Reconciliation of net income to net cash provided by operating activities
Net income	25,867,203	26,951,882
Increase in accrued income receivable	(1,562,211)	(19,035,423)
Increase in prepaid expenses	(55,167)	(39,635)
Decrease in accrued expenses	(111,401)	(38,593)
Increase in deferred royalty revenue		467,000
Net cash provided by operating activities	24,138,424	8,305,231
Non Cash Financing Activity
Distributions payable	$ 14,825,611	$ 14,694,411