Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc cua » hoc cua, thuc va
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
qua nam » quan nam, cua nam, quang nam
thuc ca » thuc can, thuc cao, thuc va
cuu tre » cua tre, cau tren, cau treo
dan va » doan va, ban va, han va

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 ky nang xa hoi. hieu qua nam ((thuc ca) or (thuc cua)) ((dan va) OR (dan ca)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu qua nam ((thuc ca) OR (thuc cua)) ((dan va) OR (dan ca)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang xa hoi. hieu qua nam ((thuc ca) or (thuc cua)) ((dan va) OR (dan ca)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu qua nam ((thuc ca) or (thuc cua)) ((dan va) OR (dan ca)) cuu tre*.