Kur Piktžolė
Šiaurės Amerika | J. Swearingen & C. Bargeron (2016) - Invasive Plant Atlas of the United States |
Europa | NOBANIS - European Network on Invasive Alien Species |
Jungtinė Karalystė ir Airija | The Biological Records Centre |
Rusija | NOBANIS - European Network on Invasive Alien Species |
Australija | R.P. Randall & O. Kessal (2004) |
Naujoji Zelandija | C. Howell (2008) - Consolidated List of Environmental Weeds in NZ |