The WorldCat search returns print and electronic books as well as various other types of media from the AMBS Library as well as libraries worldwide. You can search WorldCat without a password, but you will be asked for your password to log in to read ebooks.
The EBSCOHost search returns a variety of article results from general and special purpose academic databases. You can choose the databases that are most appropriate to your topic. Some of the articles are full text, while others need to be requested via the link to Find It at AMBS or request from other libraries.
The Atlas Plus search specifically focuses on topics like theology, religious studies, church history, biblical studies, and mission. A lot of the articles in this database are full text, but some will need to be requested as scans via the Find It link. A very cool feature of the Atlas Plus database is the ability to search by Scripture text for articles that relate to your passage. Atlas Plus also includes a wide variety of scholarly articles on religion and related disciplines from around the world in many languages as well as from a wide variety of faith traditions.
JSTOR is a full text backfile of fairly serious academic journals, with a strong focus in humanities disciplines.