Perhaps you should try some spelling variations:
nam truc » nam truoc, nam thuc, nam trung
cau tren » cu tren, dau tren, ca tren
cao hoc » co hoc, cho hoc, chat hoc
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau treo
sac ky » cac ky, sai ky
va nam » van nam, ha nam, va nay

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sac ky) or (sach y)) nang cao hoc. lieu va nam truc va hanh vi ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sac ky) OR (sach y)) nang cao hoc. lieu va nam truc va hanh vi ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sac ky) or (sach y)) nang cao hoc. lieu va nam truc va hanh vi ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: su ((sac ky) or (sach y)) nang cao hoc. lieu va nam truc va hanh vi ((cuu tre) OR (cau tren))*.