http://www.databaseanswers.org/data_models/
I've used this before just to get an idea; but experience and the end-goal matters a lot in database design.
I've heard this book is good, but havent purchased it yet: http://www.amazon.com/Data-Model-Resource-Book-Vol/dp/0470178450/ref=pd_sim_b_2?ie=UTF8&refRID=0CQ088ZFPFKKTMR9CKQ7
I highly recommend http://www.amazon.com/Data-Model-Resource-Book-Vol/dp/0470178450/ref=sr_1_2?ie=UTF8&qid=1458584943&sr=8-2&keywords=universal+data+models
It's a deep dive, you will learn a lot. Most DBAs (I'm looking at you, Oracle consultants,) don't know these patterns for database design very well, if at all.