Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
y nang » ky nang, ly nang, v nang
ve cac » va cac, vien cac
va dan » ca dan, va dao, va dau
du va » dau va, tu va, su va
ca su » cua su, cao su, ca sau

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 hoi. hieu ve cac du va dan ca su (kien OR tien)~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang xa hoi. hieu ve cac du va dan ca su (kien OR tien)".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang xa hoi. hieu ve cac du va dan ca su (kien OR tien)*.