Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
thu sach » tu sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
thanh vi » hanh vi, thanh va, thanh ve
va thanh » gia thanh, ban thanh, va tinh
tac dao » toc dao, tac da, tac bao
tac dat » tac da, tac dau, tat dat
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (thuat sach)) ky nang ma hoi. hieu van ((tac dat) OR (tac dao)) va thanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuat sach)) ky nang ma hoi. hieu van ((tac dat) OR (tac dao)) va thanh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thuat sach)) ky nang ma hoi. hieu van ((tac dat) OR (tac dao)) va thanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuat sach)) ky nang ma hoi. hieu van ((tac dat) OR (tac dao)) va thanh vi cua vat*.