APA Format
Kallen, Anders . (). Understanding...: Observational studies and the need for clinical trials. ( Ket. lihat halaman 29-56 ) ( Bab. 2 ) . : Sweden: Department of biostatistics, 2011
MLA Format
Kallen, Anders . Understanding...: Observational studies and the need for clinical trials. ( Ket. lihat halaman 29-56 ) ( Bab. 2 ) . : Sweden: Department of biostatistics, 2011,
Australian/Harvard Format
Kallen, Anders . . Understanding...: Observational studies and the need for clinical trials. ( Ket. lihat halaman 29-56 ) ( Bab. 2 ) . Sweden: Department of biostatistics, 2011, 
Warning: These citations may not always be 100% accurate.