These are more general texts that you may already have (readily available and not too expensive) which have useful sections on stress.
Specific stress texts
The development of technique
(a) Interviewing technique
You have to get information before you can give help. Although you are not expected to be able to diagnose according to the DSM (Diagnostic and Statistical Manual) for this module many of the best books are for clinical practitioners.
(b) Nutrition
A good diet provides a solid foundation for stress reduction.
