Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
nang xa » lang xa, nang ma, mang xa
van cam » van nam, van lam, van cau
tai cua » thai cua, tai cuc, tri cua
xuc va » duc va, tuc va, luc va
cua te » cua tu

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 y ((nang xa) or (nang x)) hoi. hieu van cam ((xuc va) or (tuc xa)) hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((nang xa) OR (nang x)) hoi. hieu van cam ((xuc va) OR (tuc xa)) hanh tai cua te.
• Adding a wildcard symbol may retrieve word variants: toc sach y ((nang xa) or (nang x)) hoi. hieu van cam ((xuc va) or (tuc xa)) hanh tai cua te*.