Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
cuu tre » cua tre, cau treo
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang x) or (lang xa)) hoi. hieu va cam duc va danh vi ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang x) OR (lang xa)) hoi. hieu va cam duc va danh vi ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang x) or (lang xa)) hoi. hieu va cam duc va danh vi ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang x) or (lang xa)) hoi. hieu va cam duc va danh vi ((cuu tre) OR (cau tren))*.