Presidential appointments
Section 171(2)(d) · 1999 Constitution (2004 edition)
What Constitution says
(d) Permanent Secretary in any Ministry or Head of any Extra-Ministerial Department of the Government of the Federation howsoever designated; and
This is the 1999 Constitution as published in 2004. Later amendments aren't included yet, so a section may have changed since.
Original source
Official Gazette · CFRN 1999 official PDF · printed page 81. Original document
Release: draft-c8d50d87fae9. Source scope, review and corrections