Answer:
1. Encyclopedia.
2. Online search engine.
3. Dictionary.
4. Thesaurus.
Step-by-step explanation:
1. Encyclopedia: a collection of informative articles typically arranged in an alphabetical order about a wide variety of topics from around the world. It is also referred to as Encyclopedia Britannica and could either be in form of a book or an online (electronic) database.
2. Online search engine: information stored in databases and on sites. It's an internet resource or service that searches for keywords or categories specified by the end user and then displays (shows) a list of website which matches or have informations similar to the query. Some examples of popular search engines are Goo-gle, Bing, Yahoo, etc.
3. Dictionary: a book or electronic resource that comprises of definitions, pronunciation, and spelling of words that are often arranged in an alphabetical order. Also, it provides an example on the usage of a word.
4. Thesaurus: words with similar meaning listed together. It's simply a type of book that lists words having similar meanings (synonyms) together and words that have opposite meanings (antonyms). The word "thesaurus" was derived from Greek and it means treasure.