Pengaruh Jenis Kelamin, Usia, dan Data Antropometri terhadap Landmark Blok Popliteal pada Ras melayu di Indonesia : Penelitian Observasional dengan panduan Ultrasonografi = Influence of Gender, Age, And Anthropometric Data on Popliteal Block Landmark on Malay Race in Indonesia : An Observational Research with Ultrasound Guidance