Yes, the legal references regarding this are hard to find.. This also states that the right exists:
http://ec.europa.eu/justice/citizen/fil ... _ec_en.pdf
Under the Directive your family members, irrespective of their
nationality, are entitled to take up employment or self-employment in the host Member State. It does not matter whether
you work, study or just reside there, your family members can start
their economic activity with the same paperwork as nationals.
Your family members, legally residing with you have free access
to the labour market of the Member State concerned without work
permits once they have been resident there for at least eighteen
months or from 1 May 2007, whichever is the earlier. If they do not
meet this condition, they still may work, but they need to acquire a
work permit.