Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cac thoi » cac toi, cac hop, cac tro
hang doi » hang di, hang loi, huong doi
cau tren » cu tren, dau tren, ca tren
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cac thu » cach thuc
va hang » van hang, va nang, va lang
doi cau » doi dau, di cau, doi ca

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 tu nang xa hoi. hieu va ((cac thu) OR (cac thoi)) va hang doi cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tu nang xa hoi. hieu va ((cac thu) OR (cac thoi)) va hang doi cau tren".
• Adding a wildcard symbol may retrieve word variants: toc sach tu nang xa hoi. hieu va ((cac thu) OR (cac thoi)) va hang doi cau tren*.