Perhaps you should try some spelling variations:
va thanh » ban thanh, va tinh, le thanh
cam thuc » am thuc, nam thuc, cam thu
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
chu tre » cho tre, chu tri, cuu tre
hieu ve » hieu va, hieu van
tang ma » mang may, tang van
nang xa » nang x, lang xa, nang ma
va chu » va che, va cau, va chi
ve cam » ve cham, ve cac, va cam

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 ky ((nang xa) or (tang ma)) hoi. hieu ve cam thuc ((va thanh) OR (gia thanh)) va chu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang xa) OR (tang ma)) hoi. hieu ve cam thuc ((va thanh) OR (gia thanh)) va chu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang xa) or (tang ma)) hoi. hieu ve cam thuc ((va thanh) OR (gia thanh)) va chu tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang xa) or (tang ma)) hoi. hieu ve cam thuc ((va thanh) OR (gia thanh)) va chu tre*.