Internet, http://errol.oclc.org/laf/n%20%2085819693.html, 2010/05/04
The principles and practice of land drainage : embracing a brief history of underdraining
; a detailed examination of its operations and advantages ; a description of various
kinds of drains, with practical directions for their construction : the manufacture
of drain-tilr, etc. / by John H. Klippart, 1861