There are quite a few resources available, including:
A History of Railroading in Western North Carolina by Gary Franklin Poole (1995). (The text does not discuss the Elkin & Allegheny of Burch, NC, the Watauga & Yadkin of North Wilkesboro, nor the 3’ gauge Mt. Airy & Eastern.)
Watauga & Yadkin River Railroad by Matthew Bumgarner and R. Douglas Walker (Tarheel Press, 2003).
The Lawndale Railway & Industrial Company by Matthew Bumgarner, Ladley Burn, et. al. (N.C. Railroad Heritage Publishing Co., 1999).
Legacy of the Carolina & North-Western Railway by Matthew Bumgarner (The Overmountain Press, 1996).
Last Train to Elkmont by Vic Weals (Great Smokey Mountains area), (Olden Press, 1991)
Mount Mitchell: It’s Railroad & Toll Road by Jeff Lovelace (Overmountain Press, 1994)
Logging Railroads of the Blue Ridge and Smokey Mountains, Vol. 1 and Vol. 2 by Thomas Fetters (Timber Times, 2007 & 2010) - likely the most complete source on logging railroads of this area.
Also of potential interest would be: Railroading in the Carolina Sandhills, 3 volumes by S. David Carriker, Cape Fear & Yadkin Valley Ry (reprinted 2000 by N.C. Railroad Heritage Publishing Co. of Hickory, NC., and then, of course, books concerning major railroads that traveled through this area, such as books about the Clinchfield RR.
Bill