Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang xa » nang x, lang xa, nang ma
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
dan vai » dan va, dan vat, den vai
dan tai » van tai, dan thi, han tai
cuu tre » cua tre, cau tren, cau treo
va nam » van nam, ha nam
va nay » va ngay, va cay

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