Richard Helmer

Born 1943-01-01

Identifiers

  • Open LibraryOL1841514A

Top Subjects

  • Filters and filtration (1)
  • Deodorization (1)
  • Soil absorption and adsorption (1)
  • Air -- Purification (1)
  • Sewage -- Purification (1)

Books by Richard Helmer

Total count: 3