Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
vat hanh » vat thanh, van hanh, va hanh
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
qua nam » quan nam, cua nam, quang nam
vi cua » vai cua, di cua
de cua » le cua, te cua, dieu cua
x hoi » xa hoi, o hoi, x ho

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 ty nang x hoi. hieu qua nam thuc vat hanh ((vi cua) or (de cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang x hoi. hieu qua nam thuc vat hanh ((vi cua) OR (de cua)) tre*.