When no title is available, write a description of the item and place it in square brackets. Put this information where you would normally put the title.
Reference
Jones, B. D., Smith, R. J., & Robertson, V. (n.d.). [Description of childhood trauma]. Retrieved from http://childhood-trauma-information.org/define.htm
In-text Citation
(Jones, Smith, & Robertson, n.d., para. 6).