Perhaps you should try some spelling variations:
sach tham » sach nha
toc sach » hoc sach, doc sach, thuoc sach
cam truc » cau truc, nam truc, lam truoc
hanh vai » hanh vi, hanh va, hanh tai
cua tre » cuu tre, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
va cam » va cham, va cac, va cao
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach tham ((nang xa) or (nang ma)) hoi. hieu va cam truc va hanh vai ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tham ((nang xa) OR (nang ma)) hoi. hieu va cam truc va hanh vai ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tham ((nang xa) or (nang ma)) hoi. hieu va cam truc va hanh vai ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: toc sach tham ((nang xa) or (nang ma)) hoi. hieu va cam truc va hanh vai ((cua tre) OR (cua te))*.