Jared Hoyle; Ross Braun (February 2018). "Aerating Your Lawn"(PDF). K-State Research and Extension. MF2130.
ncsu.edu
pitt.ces.ncsu.edu
Lauderdale, Danny; Roberson, Sarah. "Happy Gardening! You Have Earthworms!". NC Cooperative Extension. North Carolina State University. Archived from the original on 27 October 2017. Retrieved 20 October 2017.
web.archive.org
Lauderdale, Danny; Roberson, Sarah. "Happy Gardening! You Have Earthworms!". NC Cooperative Extension. North Carolina State University. Archived from the original on 27 October 2017. Retrieved 20 October 2017.