Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hanh tai » thanh tai, hang tai, han tai
cao tren » ca tren, cau tren, cao thien
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
cao hoc » co hoc, cho hoc, chat hoc
thuc xa » thuc xay, tuc xa, thuc va
xa hanh » xa thanh, xa khanh, va hanh
co tren » cu tren, do tren, ca tren

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 ky) or (sach ty)) nang cao hoc. liem ha nam thuc xa hanh tai ((cao tren) OR (co tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) nang cao hoc. liem ha nam thuc xa hanh tai ((cao tren) OR (co tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sach ty)) nang cao hoc. liem ha nam thuc xa hanh tai ((cao tren) OR (co tren))".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach ty)) nang cao hoc. liem ha nam thuc xa hanh tai ((cao tren) OR (co tren))*.