Attached Link: Gottfried Bammes

For human and animal anatomy, everything by Gottfried Bammes.

As a Professor at the Academy of Arts in Dresden in (former) East-Germany, he was neither influenced by the desire to idealise the human shape to sell more products nor by religious queasiness.

 You want to go beyond "pretty" and see how things really are, give his books a try.

 

For everthing mechanical, Google will provide everything from blueprints to real world measurments with a few mouseclicks, so there is really no excuse for "eyeballing" anything.

If you want more in-depth knowledge about certain subjects, books for scale-modelers are just as useful for cgi-modeling as they are for "actual" modeling.