Perhaps you should try some spelling variations:
tan hanh » tan thanh, tang hanh, toan hanh
tu sach » thu sach, su sach, te sach
ly nang » ky nang, ly hang, ly quang
ly vang » ly hang, ly van, ly quang
hieu va » lieu va, hieu qua
va giao » van giao, va giai, va gia
vai cua » dai cua, lai cua, bai cua
hai cua » thai cua, dai cua, hoi cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((ly nang) OR (ly vang)) xa hoi. hieu va giao duc tan hanh ((vai cua) or (hai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ly nang) OR (ly vang)) xa hoi. hieu va giao duc tan hanh ((vai cua) OR (hai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ly nang) OR (ly vang)) xa hoi. hieu va giao duc tan hanh ((vai cua) or (hai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ly nang) OR (ly vang)) xa hoi. hieu va giao duc tan hanh ((vai cua) or (hai cua)) tre*.