Perhaps you should try some spelling variations:
dan khanh » dang khanh, van khanh, dat khanh
khanh dai » thanh dat, khanh van, phan dai
thu sach » thuat sach, thuoc sach, thu hoach
doc sach » hoc sach, toc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
tu sach » su sach, te sach, tu cach
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
nam hoc » nam moc, nam hoi, am hoc
cua tre » cua te, cuu tre, cua triet

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) or (thu sach))) or (doc sach)) ky lang xa hoi. hieu van nam hoc dan khanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((tu sach) OR (thu sach))) OR (doc sach)) ky lang xa hoi. hieu van nam hoc dan khanh dai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((((tu sach) or (thu sach))) or (doc sach)) ky lang xa hoi. hieu van nam hoc dan khanh dai cua tre*.