Perhaps you should try some spelling variations:
trinh vat » trinh van, trinh luat, sinh vat
toc sach » hoc sach, thuoc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
doc sach » hoc sach, nuoc sach, dac sac
tang mai » tang ma, tang tai, lang mai
mai hoi » mai khoi, dai hoi, lai hoi
van cam » van nam, van lam, van cau
vat cua » mat cua, bat cua, dat cua
cua tre » cua te, cuu tre, cua triet
y tang » ky tang, 6 tang, 7 tang
tuc va » thuc va, truc va, tuc xa

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) or (doc sach)) y tang mai hoi. hieu van cam ((tuc va) or (duc va)) trinh vat cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) y tang mai hoi. hieu van cam ((tuc va) OR (duc va)) trinh vat cua tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) y tang mai hoi. hieu van cam ((tuc va) or (duc va)) trinh vat cua tre*.