This blog provides relevant research discussing various grip positions, the muscles worked with the lat pulldown, and proper form of the movement.
Medium-grip lat pull-down exercise instructions and video
Straight-Arm Pulldowns: Tips and Recommended Variations
PDF) A Comparative Analysis and Technique of the Lat Pull-down
Puxada em pé com a toalha - Como fazer e erros comuns - MundoBoaForma
How To: Chest Supported Lat Pulldown (Build Lower Lats)
How Pullups Work (WIDE GRIP, STANDARD, & CHIN-UP BIOMECHANICS
PDF) A Comparative Analysis and Technique of the Lat Pull-down
Puxada invertida na máquina de cabos - Como fazer e erros comuns - MundoBoaForma
Exploring Lat Pulldown Grip Variations for Ultimate Back