Effect of using fresh palm oil and used palm oil as a fatliquoring agent to the physical quality of tilapia fish skin in vegetable tanneryAmbar Pertiwiningrum, Kurniawan Eko Nugroho, Muhammad Aziz Nur Roufi, Viagian Pastawan, Ragil Yuliatmo, Mohammad Zainal Abidin and Yuny ErwantoE3S Web Conf., 335 (2022) 00008DOI: https://doi.org/10.1051/e3sconf/202233500008