Perhaps you should try some spelling variations:
thanh tap » thanh lap, thanh tai, thanh tay
hieu van » hieu va, thien van, lieu va
cua viet » hoa viet, cua vat, cua dieu
va thanh » gia thanh, ban thanh, va tinh
hac duc » hoc duc, ha duc, thach duc
van hac » van hoc, van ha, van hai
tu sach » thu sach, su sach, te sach
ty hang » ly hang, ty xang, thi hang
ty nang » ky nang, ty xang, ly nang
ca viet » va viet, co viet, hoa viet
o hai » co hai, so hai, o lai

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) OR (ty hang)) o hai. hieu van hac duc va thanh tap ((cua viet) or (ca viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ty hang)) o hai. hieu van hac duc va thanh tap ((cua viet) OR (ca viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) OR (ty hang)) o hai. hieu van hac duc va thanh tap ((cua viet) or (ca viet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) OR (ty hang)) o hai. hieu van hac duc va thanh tap ((cua viet) or (ca viet))*.