Pharmaceutical Medicine Dictionary defines primary sources as:
1. Scientific refereed journal: A journal that has a mission of publishing and storing primary scientific evidence. By convention primary sources include: evidence published in such a journal is subjected to anonymous review by several experts (referees) in the field prior to publication and is published only once. 2. Scientific proceedings: A compilation of current research reports, typically presented as short abstracts, from a scientific meeting.
Secondary sources are defined as an information source that does not have as a major component the description of formal observations or experiments but rather is synthesized from some combination of primary sources, experience, or authoritative belief (dogma).
Tertiary sources are a compilation of information for application across a broad spectrum typically represented by class notes and textbooks intended for use in core courses.
It is advisable to consult your instructor to determine whether a source is acceptable.