Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
van cam » van nam, van cau, van dam
van lam » van nam
ma hoi » mai hoi, xa hoi, ma hoa
luc va » duc va, tuc va, loc va
va han » va phan, van han, va hanh
tai va » thai va, tri va, dai 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 ma hoi. hieu ((van cam) or (van lam)) luc va han ((tai va) OR (mai va)) thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. hieu ((van cam) OR (van lam)) luc va han ((tai va) OR (mai va)) thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ma hoi. hieu ((van cam) or (van lam)) luc va han ((tai va) OR (mai va)) thiet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu ((van cam) or (van lam)) luc va han ((tai va) OR (mai va)) thiet*.