Krag, S. & Raja, R. (2019). "Unveiling Female Hairstyles: Markers of Age, Social Roles, and Status in Funerary Sculpture from Palmyra", Zeitschrift für Orient-Archäologie, 11, 243-277.

From the abstract:

"This article explores a significant group of female funerary representations depicted with unveiled heads. It is discussed whether these representations were intended to indicate age and a certain stage in life - a trait which is otherwise almost absent in Palmyrene funerary reliefs. Furthermore it is discussed whether these portraits indicated certain social roles."