Perhaps you should try some spelling variations:
tan thanh » tran thanh, tang thanh, toan thanh
sach doi » sach hoi, sach moi, sach dao
doi nang » dai nang, hoi nang, voi nang
giai duc » giao duc, gia duc, giap duc
tan hanh » tang hanh, toan hanh, tran hanh
vu sach » vu bach, su sach, vu khach
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
vai cua » hai cua, lai cua, bai cua
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach doi nang ma hoi. hieu va giai duc ((tan hanh) OR (tan thanh)) ((vai cua) OR (dai cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach doi nang ma hoi. hieu va giai duc ((tan hanh) OR (tan thanh)) ((vai cua) OR (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: vu sach doi nang ma hoi. hieu va giai duc ((tan hanh) OR (tan thanh)) ((vai cua) OR (dai cua)) tre*.