Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
van pham » san pham, van phan, van tham
van phat » va phat, van chat, van phan
tu sach » su sach, te sach, tu cach
cao hoi » cau hoi, co hoi, cao hoc
thuc va » thuc vat, thuc dan, thuc day
dan hai » doan hai, dang hai, dan khai
va dan » ca dan, va dao, va dau
hai va » hai van, thai va, hoi 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) or (thu sach)) ky nang cao hoi. hieu ((van pham) OR (van phat)) thuc va dan hai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang cao hoi. hieu ((van pham) OR (van phat)) thuc va dan hai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ky nang cao hoi. hieu ((van pham) OR (van phat)) thuc va dan hai va thiet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang cao hoi. hieu ((van pham) OR (van phat)) thuc va dan hai va thiet*.