[1]. Howard, J. (2001). U.S.timber production, trade, consumption and price statistics 1965-1999. Res. Pap.FPL-RP-595, Madison, WI. U.S. Department of Agriculture, Forest Service, Forest Product Laboratory.
[2]. Paun, D., and Jackson, G. (2000). Potential for expanding small-diameter timber market - assessing use of wood posts in highway applications. Gen.Tech.Rep. FPL-GTR-120., Madison, WI. U.S. Department of Agriculture, Forest Service, Forest Product Laboratory.
[3]. Willits, S., and Ross, R. (2004). Veneer recovery from small diameter stands in south western Oregon. USDA forest service, Pacific Northwest Research Station and Forest Products Laboratory, WI, 39:172-185.
[4]. Bayatkashkoli, A., Amiri, S., Faezipour, M., and Dosthosyne, K. (2008). Economical classification of small-diameter poplar utilization in the particle board and ply wood industries. Iranian Journal of Natural Resources, 81:87-99.
[5]. Amiri, S. (2000). Defects investigation and determine of allowable measured of defects in log grading. Iranian Journal of Natural Resources, 53(2):113-129.
[6]. Bayatkashkoli, A., Amiri, S., and Parsapajouh, D. (2007). Grading and scaling methods of log and lumber. Ilaf Press, Shiraz.
[7]. Bodig, J., and Jayne, B. (1989). Mechanics of wood and wood composites. Translated by Ebrahimi, Gh., University of Tehran Press, Second Edition, Tehran.
[8]. Becker, D. (1998). Lumber recovery from small diameter ponderosa pine in northern Arizona. Pacific Northwest Research, Southern Research Station, General Technical Report PNW- GTR.44: 123-134.
[9]. Wang, S.Y., Chen, J.H., Tsai, M.J., Lin, C.J., and Yang, T.H. (2008). Grading softwood lumber using nondestructive techniques. Journal of Materials Processing Technology, 208: 149–157.
[10]. Divos, F., and Tanaka, T. (1997). Lumber strength estimation by multiple regression. Holzforschung, 51: 467–471.
[11]. Structural Timber-Strength classes, Committee European National (CEN), EN 338, 2003.
[12]. Fernandez-Golfin, J.I., Diez-Barra, M.R., Hermoso, E., and Mier, R. (2007). Mechanical characterization of visually classified small- diameter laricio pin round timber. Spanish Journal of Agricultural Research, 5(3): 304-311.
[13]. Acceptable defects for logs (and gradation), Institute of Standards and Industrial Research of Iran, ISIRI Number 1275, 1994.
[14]. Wood – Hardwood baulk – Gradation, Institute of Standards and Industrial Research of Iran, ISIRI Number 8073, 2004.