Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
tu sach » su sach, te sach, tu cach
nang co » nang cao, nang doc, nang noi
thuc va » thuc dan, thuc day
dan mai » doan mai, ban mai, dan tai
co hoi » co hoc, co loi
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) or (thu sach)) ky nang co hoi. hieu van pham ((thuc va) or (thuc vat)) dan mai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang co hoi. hieu van pham ((thuc va) OR (thuc vat)) dan mai va thiet.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang co hoi. hieu van pham ((thuc va) or (thuc vat)) dan mai va thiet*.