PENGARUH PENAMBAHAN ASAM SITRAT DALAM RANSUM SEBAGAI ACIDIFIER TERHADAP RETENSI KALSIUM DAN FOSFOR ITIK JANTAN LOKAL (The Effect of Citric Acids Addition in Diets as Acidifier on Calcium and Phospor Retention of The Local Male Ducks) - Yendy, Siti Aminah (Animal Agriculture Journal, 2016)