Conjunctions, defined, 52; coordinating, 52; subordinating, 53, (not omitted) p. 34, ftn.
"A Complete Grammar of Esperanto" by Ivy Kellerman Reed
Subordinate Conjunctions are treated in connection with Subordinate Clauses.
"New Latin Grammar" by Charles E. Bennett
Use conjunctions rather sparingly, especially these subordinate conjunctions.
"Plain English" by Marian Wharton