Environmental forensic techniques in identifying the sources of 16 USEPA priority pollutants Polycyclic Aromatic Hydrocarbons (PAHs) at the Langat River, Selangor, Malaysia by Tahir, Nurul Afiqah Mohamd, Juahir, Hafizan, Zakaria, Mohamad Pauzi, Retnam, Ananthy, Sing, Tan Sin, Manan, Ninie Suhana Abdul, Toriman, Mohd Ekhwan, Ismail, Azimah, Kamarudin, Mohd Khairul Amri, Ghazali, Adiana, Wahab, Noor Abd