Gambaran efek pelatihan 'Resident as Teacher (RaT)' terhadap kemampuan membimbing chief resident: suatu pendekatan kualitatif di Program Pendidikan Dokter Spesialis Penyakit Dalam Fakultas Kedokteran Universitas Indonesia = Effect of resident as teacher training to improve teaching skills of internal resident chief resident: a qualitative study in Internal Medicine Residency Program Faculty of Medicine Universitas Indonesia