Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
den hanh » den thanh, dan hanh, deu hanh
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
thu den » thu dien, thuy den, tu den
tai cua » thai cua, tri cua, dai cua
ma hoi » mai hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty nang ((ma hoi) OR (xa hoi)). hieu van nam thu den hanh ((tai cua) or (tai cuc)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((ma hoi) OR (xa hoi)). hieu van nam thu den hanh ((tai cua) OR (tai cuc)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((ma hoi) OR (xa hoi)). hieu van nam thu den hanh ((tai cua) or (tai cuc)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((ma hoi) OR (xa hoi)). hieu van nam thu den hanh ((tai cua) or (tai cuc)) tre*.