You can find central regulations here:

Nursing Professions Act (PflBG, in particular in §§ 1, 2, 4, 40 – 48 PflBG and the annex to § 41 Para. 1 Sentence 1 PflBG) and in the Nursing Professions Training and Examination Ordinance (PflAPrV, in particular in §§ 42 – 49 PflAPrV).