Perhaps you should try some spelling variations:
truc ngan » tu ngan, thu ngan, tri ngan
sach ty » sach tu, sach thu, xach tay
hieu va » lieu va, hieu qua
hang di » hang doi, hang vi, hang dien
ca tren » cau tren, cu tren, co tren
la tren » loai tren, dua tren, dat tren
va cau » van cau, va cac, va dau
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: tu ((sach ty) OR (sach y)) nang x hoi. hieu va cau truc ngan hang di ((ca tren) or (la tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach y)) nang x hoi. hieu va cau truc ngan hang di ((ca tren) OR (la tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach y)) nang x hoi. hieu va cau truc ngan hang di ((ca tren) or (la tren))".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach y)) nang x hoi. hieu va cau truc ngan hang di ((ca tren) or (la tren))*.