Statements of Cash Flows - USD ($)	6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Operating activities
Royalties received	$ 4,799,327	$ 15,025,100
Interest received	37,338	137,704
Expenses paid	(1,214,976)	(1,315,916)
Net cash from operating activities	3,621,689	13,846,888
Investing activities
Maturities of U.S. Government securities	26,899,691	32,122,312
Purchases of U.S. Government securities	(23,708,865)	(16,484,759)
Net cash from investing activities	3,190,826	15,637,553
Financing activity
Distributions to unitholders	(16,531,213)	(29,913,623)
Net change in cash and cash equivalents	(9,718,698)	(429,182)
Cash and cash equivalents, beginning of period	10,177,655	881,810
Cash and cash equivalents, end of period	458,957	452,628
Reconciliation of net income to net cash from operating activities
Net income	8,287,624	18,821,975
Increase in accrued income receivable	(979,139)	(1,481,571)
Increase in contract asset	(1,059,624)	(3,166,721)
Increase in prepaid expense	(161,533)	(116,226)
Increase (decrease) in accrued expenses	46,081	(210,569)
Decrease in contract liability	(2,511,720)
Net cash from operating activities	3,621,689	13,846,888
Non cash financing activity
Distributions declared and payable	$ 656,001	$ 2,755,202