Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
sach kem » hanh kem
sang tai » hang tai, sang tao, tang tai
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
ve tham » va tham, ve cham, vi tham
hieu ve » hieu va, hieu van
tai hai » thi hai, dai hai, tai ha
sac ky » cac ky, sai ky
vi cua » vai cua, di cua
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: su ((sach kem) or (sac ky)) sang tai hai. hieu ve tham thuc ((va danh) OR (va hanh)) vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach kem) OR (sac ky)) sang tai hai. hieu ve tham thuc ((va danh) OR (va hanh)) vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach kem) or (sac ky)) sang tai hai. hieu ve tham thuc ((va danh) OR (va hanh)) vi cua te".
• Adding a wildcard symbol may retrieve word variants: su ((sach kem) or (sac ky)) sang tai hai. hieu ve tham thuc ((va danh) OR (va hanh)) vi cua te*.