Perhaps you should try some spelling variations:
thien van » thi van
lam truoc » lam thuoc, nam truoc, lam truong
nang hoc » nang doc, nang luc, dong hoc
truoc xa » truoc xay, truoc bua, truoc dam
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hoc hoi » hoc khoi, hoc hoa, hoc noi
hieu va » lieu va, hieu qua
xa hanh » xa thanh, xa khanh, va hanh
vai va » mai va, dai va, hai va
vi va » vi van, vu va, bi va
thiet » thieu

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 ky nang hoc hoi. ((thien van) or (hieu va)) lam truoc xa hanh ((vi va) or (vai va)) thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang hoc hoi. ((thien van) OR (hieu va)) lam truoc xa hanh ((vi va) OR (vai va)) thiet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang hoc hoi. ((thien van) or (hieu va)) lam truoc xa hanh ((vi va) or (vai va)) thiet*.