. "2001-03-22" . "Water supply / Alan C. Twort, Don D. Ratnayaka, Malcolm J. Brandt.-5th ed., 2000. - . - BLNA, 2000-12. - . -"@fr . . "Ratnayaka" . . . "2013-07-31" . . "Don D. Ratnayaka"@fr . . . . . . "13612039"^^ . . . "2013-07-31"^^ . . . . "Don D." . "Don D. Ratnayaka" . . "0000000116216509" . . "VIAF" . .