Condensed Statements of Cash Flows - USD ($)	6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017
Operating activities
Royalties received	$ 16,056,417	$ 8,723,576
Interest received	51,515	12,571
Expenses paid	(735,803)	(670,622)
Net cash from operating activities	15,372,129	8,065,525
Investing activities
Maturities of U.S. Government securities	24,168,903	82,628
Purchases of U.S. Government securities	(18,273,425)	(1,993,386)
Net cash from (used for) investing activities	5,895,478	(1,910,758)
Financing activity
Distributions to unitholders	(21,385,616)	(9,052,807)
Net change in cash and cash equivalents	(118,009)	(2,898,040)
Cash and cash equivalents, beginning of period	314,835	13,695,168
Cash and cash equivalents, end of period	196,826	10,797,128
Reconciliation of net income to net cash from operating activities
Net income	25,187,303	18,468,879
Increase in accrued income receivable	(6,820,424)	(6,175,819)
Increase in contract asset	(2,907,643)	(1,993,037)
Increase in prepaid expense	(97,625)	(86,177)
Increase (decrease) in accrued expenses	10,518	(48,906)
Decrease in contract liability		(2,099,415)
Net cash from operating activities	15,372,129	8,065,525
Non cash financing activity
Distributions declared and payable	$ 2,886,402	$ 2,099,202