Perhaps you should try some spelling variations:
cua triet » cua viet, va triet
su triet » su viet, su tien, ve triet
cam thuc » am thuc, nam thuc, cam thu
van hang » van khang, van hoang, van thang
hieu van » hieu va, thien van, lieu va
thuc van » thuc vat, thuc dan, thuc va
hang de » hoang de, hanh de, hang di
tu sach » thu sach, te sach, tu cach
nang ma » tang ma, sang ma, nang cao
su sach » so sach, vu sach
van cam » van nam, van lam, van cau

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 (su sach)) ky nang ma hoa. hieu van cam thuc van hang de ((cua triet) OR (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang ma hoa. hieu van cam thuc van hang de ((cua triet) OR (su triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang ma hoa. hieu van cam thuc van hang de ((cua triet) OR (su triet))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang ma hoa. hieu van cam thuc van hang de ((cua triet) OR (su triet))*.