Perhaps you should try some spelling variations:
van cham » van chat, van tham, va cham
hieu van » hieu va, thien van, lieu va
cau tren » dau tren, ca tren, cau treo
thanh di » thanh doi, thanh de, thanh do
cham hoc » cham soc, chat hoc, cham hoi
hoc gia » hoc giao, hoc giai, toc gia
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
cu tren » tu tren, dua tren
sac ky » cac ky, sai ky

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