Perhaps you should try some spelling variations:
van cham » van chat, van tham, van pham
han tai » hang tai, nhan tai, van tai
thuc va » thuc vat, thuc dan, thuc day
va cham » va chat, va tham
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
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 x) or (nang ma)) hoi. hieu ((van cham) or (va cham)) thuc va han tai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang x) OR (nang ma)) hoi. hieu ((van cham) OR (va cham)) thuc va han tai va thiet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang x) or (nang ma)) hoi. hieu ((van cham) or (va cham)) thuc va han tai va thiet*.