Statements of Cash Flows - USD ($)	9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020
Operating activities
Royalties received	$ 44,366,652	$ 10,724,507
Interest received	522,705	38,297
Expenses paid	(2,544,191)	(1,683,487)
Net cash from operating activities	42,345,166	9,079,317
Investing activities
Maturities of U.S. Government securities	50,942,392	55,381,743
Sales of U.S. Government securities		236,992
Purchases of U.S. Government securities	(41,035,723)	(51,574,900)
Net cash from investing activities	9,906,669	4,043,835
Financing activity
Distributions to unitholders	(18,892,815)	(17,187,214)
Net change in cash and cash equivalents	33,359,020	(4,064,062)
Cash and cash equivalents, beginning of period	12,500,941	10,177,655
Cash and cash equivalents, end of period	45,859,961	6,113,593
Reconciliation of net income to net cash from operating activities
Net income	51,322,806	13,414,023
Increase in accrued income receivable	(8,241,597)	(1,113,742)
Decrease (increase) in contract asset	(374,119)	(736,137)
Increase in prepaid expense	(107,937)	(91,217)
Increase (decrease) in accrued expenses	(253,987)	118,110
Increase (decrease) in contract liability		(2,511,720)
Net cash from operating activities	42,345,166	9,079,317
Non cash financing activity
Distributions declared and payable	$ 18,630,414	$ 4,723,204