I have a small problem in schwa sound: When I used Oxford online dictionary and searched "fossil", Its pronunciation is /ˈfɒsl/, but the Cambridge Dictionaries Online gave me: /ˈfɒs. ə l/
As you can see, the schwa sound is written as a small "ə" in Cambridge dictionary, but Oxford dictionary don't write "ə". Is this a kind of abbreviation in IPA?