Perhaps you should try some spelling variations:
tham nuoc » thay nuoc, thoat nuoc, nha nuoc
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
nuoc van » nuoc va, nuoc san, luoc van
cua viet » ca viet, hoa viet, cua vat
hoc hoa » hoc khoa
sach ky » sac ky, sach y, sach ty
va tham » van tham, va cham, va thanh
hoc hoi » hoc khoi, hoc noi, hoc moi
ky dong » ly dong, ky dang, ky cong
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua

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 ky dong ((hoc hoi) OR (hoc hoa)). hieu va tham nuoc van hanh vi ((cua tre) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dong ((hoc hoi) OR (hoc hoa)). hieu va tham nuoc van hanh vi ((cua tre) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky dong ((hoc hoi) OR (hoc hoa)). hieu va tham nuoc van hanh vi ((cua tre) or (cua viet))".
• Adding a wildcard symbol may retrieve word variants: toc sach ky dong ((hoc hoi) OR (hoc hoa)). hieu va tham nuoc van hanh vi ((cua tre) or (cua viet))*.