Mamma.com ~ Google Scholar ~ ERIC Digest ~ Yahoo.com
These four search engines are useful devices in internet that can help us to obtain information shortly and fast. With typing the key word or exact phrase, these four search engines will show many information that linked to a lot of websites.
Using "The Mother of All Search Engines" as its slogan, Mamma.com is one of the useful device in obtaining information. You can say that there are not a lot of hits that one can get, but the hits or the information showed are more specific and appropriate. Furthermore, it supports advanced operator. For example, they can perform an exact operation if quotation ('' ") is used and if you want to include or exclude some terms in your search, you can simply put the plus (+) and minus (-) signs. Not just in English, Mamma.com is also available in French Language.
It can be said that Google Scholar is more into scholar itself. The information or hits showed is more academic and it is suitable for students who want to search for references of their thesis, assignment and so on. No idea why the are using the slogan "Stand on The Shoulders of The Giant", but Google Scholar can perform many hits and shows more website link compared to Mamma.com. You might want to be picky of clicking the hits found because some of the information are not really relevants and appropriate of what you want to search for.
Basically, the term ERIC is an abbreviation of Education Resources Information Center. Just like the meaning, ERIC digest is specially designed to cater the needs of educational community such as teachers, students, instructors and so on. It also provide an overview of information on a given topic, plus references to items providing more detailed information. The information or the essays also are produced by the former 16 subject-specialized ERIC Clearinghouses, and reviewed by experts and content specialists in the field.