Nomenclature problems

We have been using the following references for our collections: Tree Flora of Malaya (TFM), Foresters' Manual of Dipterocarps (FMD), A Catalogue of Vascular Plants of Malaya compiled by Ian Turner, 1995 (CVP), SING Herbarium voucher specimens (SING) and our own BTNR list of plants (CBT).

Which should be the ultimate source of reference when we encountered nomenclature problems such as these?

1 - Coll. matched Dialium indum (CBT) and D. laurinum (SING)
Is D. indum = D. indum var. indum = D. laurinum?
(CBT: D. indum, SING: D. laurinum, CVP: D. indum var. indum = D. laurinum, TFM: D. indum ≠ D. laurinum)

2 - Coll. matched G. eugeniifolia (CBT) and G. farquhariana var. eugeniifolia (SING)
Is G. eugeniifolia = G. farquhariana var. eugeniifolia?
(SING/CVP: G. farquhariana var. eugeniifolia, CBT/TFM: G. eugeniifolia)

3 - Coll. matched Aidia densiflora (SING)
(CBT/TFM: A. wallichiana, SING: A. densiflora, CVP: A. wallichiana = A. densiflora)

4 - Coll. matched Baccaurea griffithii (CBT) but there is only B. macropoda on the list (code = BACCGR.
(TFM/CVP: B. griffithii, no B. macropoda)