Cita APA (7a ed.)
Journal - American Water Works Association [J Am Water Works Assoc] NLMUID: 7505558.
Cita Chicago Style (17a ed.)
Journal - American Water Works Association [J Am Water Works Assoc] NLMUID: 7505558.
Cita MLA (9a ed.)
Journal - American Water Works Association [J Am Water Works Assoc] NLMUID: 7505558.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.