Perhaps you should try some spelling variations:
nang doc » nang luc
tu sach » thu sach, su sach, te sach
doc hoi » duoc hoi, hoc hoi, doc hai
ve cham » va cham, ve chat, ve chim
sach ky » sac ky, sach y, sach ty
vu cham » va cham, vu kham, tu cham
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
hai va » hai van, thai va, hoi va
thiet » thieu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang doc hoi. hieu ((ve cham) OR (vu cham)) truc va hanh ((hai va) OR (mai va)) thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang doc hoi. hieu ((ve cham) OR (vu cham)) truc va hanh ((hai va) or (mai va)) thiet~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang doc hoi. hieu ((ve cham) OR (vu cham)) truc va hanh ((hai va) or (mai va)) thiet*.