Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
toc sach » hoc sach, thuoc sach, nuoc sach
dua tren » dung tren
doc sach » hoc sach, nuoc sach, dac sac
thanh vi » hanh vi, thanh va, thanh ve
hieu van » hieu va, thien van, lieu va
cam duc » cam xuc, cao duc, pham duc
duc van » duc va, duc tan, duc manh
van cam » van nam, van lam, van cau
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cuu tre » cua tre, cau tren, cau treo

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) OR (doc sach)) ky lang xa hoi. hieu van cam duc van thanh vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky lang xa hoi. hieu van cam duc van thanh vi ((dua tren) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ky lang xa hoi. hieu van cam duc van thanh vi ((dua tren) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ky lang xa hoi. hieu van cam duc van thanh vi ((dua tren) or (cuu tre))*.