URL dokumen:
https://prisma.simaster.ugm.ac.id/karya_files/estrus-signs-and-estrogen-levels-in-brahman-cross-and-firstgeneration--f1--crossbred-cattle--implications-for-pregnancy-and-repeat-mating-dcfcd07e645d245babe887e5e2daa016/4e4c1928-89e1-11ef-a04f-00505691351c