Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
chu tren » cu tren, cau tren, chu trang
hieu van » hieu va, thien van, lieu va
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, sach thu
sach ky » sac ky, sach y, sach kem
van cau » van dau, van hau, van chat
truc va » thuc va, thuc vat, trung va
hai chu » hai chau, hoi chu, hai chi

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