8Ali Akbar Merati and Masaaki Okamura. Hollow Yarn in Friction Spinning Part 1:Tensile Properties of Hollow Yarn[J].Textile Research Journal,2000;70(12):1070~1076.
9Ali Akbar Merati and Masaaki Okamura. Hollow Yarn in Friction Spinning Part 2:Yarn Structure and Deformation Under Axial Tension and Lateral Forces[J]. Textile Research Journal, 2001;71(5):454~458.