Perhaps you should try some spelling variations:
phap trinh » lap trinh, phap sinh, phap dinh
phap tinh » phap sinh, phap tieng, phap tang
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
vat cua » mat cua, bat cua, dat cua
van lam » van nam
lam hoc » am hoc, lam hoa, tam hoc
sach ky » sac ky, sach y, sach ty
lang ha » long ha
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 ky ((lang ha) or (nang x)) hoi. hieu van lam hoc ((phap trinh) OR (phap tinh)) vat cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((lang ha) OR (nang x)) hoi. hieu van lam hoc ((phap trinh) OR (phap tinh)) vat cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((lang ha) or (nang x)) hoi. hieu van lam hoc ((phap trinh) OR (phap tinh)) vat cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((lang ha) or (nang x)) hoi. hieu van lam hoc ((phap trinh) OR (phap tinh)) vat cua tre*.