Wegelius, T. (1939). The presence and properties of knots in Finnish spruce: Investigations concerning the origin and characteristics of branch and knot wood in Finnish spruce with particular consideration given to the raw material needs of the paper industry.

Wegelius, Th. The Presence and Properties of Knots in Finnish Spruce: Investigations Concerning the Origin and Characteristics of Branch and Knot Wood in Finnish Spruce with Particular Consideration Given to the Raw Material Needs of the Paper Industry. Helsinki, 1939.

Wegelius, Th. The Presence and Properties of Knots in Finnish Spruce: Investigations Concerning the Origin and Characteristics of Branch and Knot Wood in Finnish Spruce with Particular Consideration Given to the Raw Material Needs of the Paper Industry. 1939.