Source
Porter, Carpentry and Joinery (2001)
Brian Porter (2001), Carpentry and Joinery 1, Third edition, Oxford; Waltham (MA), Butterworth-Heinemann.
Additional Reference
p. 44
Brian Porter (2001), Carpentry and Joinery 1, Third edition, Oxford; Waltham (MA), Butterworth-Heinemann.
p. 44