Statements of Cash Flows - USD ($)	9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018
Operating activities
Royalties received	$ 27,121,064	$ 34,316,372
Interest received	176,140	74,962
Expenses paid	(1,695,941)	(1,054,741)
Net cash from operating activities	25,601,263	33,336,593
Investing activities
Maturities of U.S. Government securities	37,034,247	28,893,900
Sales of U.S. Government securities		99,740
Purchases of U.S. Government securities	(30,473,442)	(37,767,613)
Net cash from investing activities	6,560,805	(8,773,973)
Financing activity
Distributions to unitholders	(32,668,825)	(24,272,019)
Net change in cash and cash equivalents	(506,757)	290,601
Cash and cash equivalents, beginning of period	881,810	314,835
Cash and cash equivalents, end of period	375,053	605,436
Reconciliation of net income to net cash from operating activities
Net income	24,972,171	38,772,365
Increase in accrued income receivable	(69,219)	(4,154,875)
Decrease (increase in contract asset	56,357	(1,263,633)
Increase in prepaid expense	(61,816)	(40,703)
Increase (decrease) in accrued expenses	(234,359)	23,439
Increase in contract liability	938,129
Net cash from operating activities	25,601,263	33,336,593
Non cash financing activity
Distributions declared and payable	$ 11,414,408	$ 12,332,809