Hirst Adrian & OH learning.com. Basic principles of occupational hygiene.
Lua i Stíl Chicago (17ú heag.)Hirst Adrian agus OH learning.com. Basic Principles of Occupational Hygiene.
Lua MLA (9ú heag.)Hirst Adrian agus OH learning.com. Basic Principles of Occupational Hygiene.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.