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