Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
kho tang » cao tang
hieu van » hieu va, thien van, lieu va
van cam » van nam, van lam, van cau
cam tuc » cam xuc, cam tu, nam thuc
va hanh » van hanh, va thanh, va danh
ky tang » ky nang, ky dang, ky trong
tai cua » thai cua, tai cuc, dai cua
tuc va » thuc va, truc va, tuc xa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ((ky tang) or (kho tang)) xa hoi. hieu van cam tuc va hanh ((tai cua) OR (tri cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky tang) OR (kho tang)) xa hoi. hieu van cam tuc va hanh ((tai cua) OR (tri cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky tang) or (kho tang)) xa hoi. hieu van cam tuc va hanh ((tai cua) OR (tri cua)) te".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky tang) or (kho tang)) xa hoi. hieu van cam tuc va hanh ((tai cua) OR (tri cua)) te*.