You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "who is the original singer of i heard it through the grapevine?" whose answer is Gladys Knight & the Pips.
Each document should contain about 30 words, and these documents should contain useful information.

Query: original singer of i heard it through the grapevine
Useful Output:

Doc 1: Marvin Gaye - I Heard It Through The Grapevine (Lyric Video) · Comments866.
Doc 2: Marvin Gaye was not the first Motown artist to record it. Smokey Robinson and the Miracles recorded it first. Marvin Gaye recorded his version
Doc 3: Gladys Knight & The Pips - I Heard It Through The Grapevine (Lyric Video) · Comments.
Doc 4: Knight. Miracles. Gaye. Funny that so many people think the Marvin Gaye version is the original, but it sure is iconic. Upvote 49. Downvote
Doc 5: A heady mix of loss, defiance and lust, Gaye's only UK No 1 is a testament to the Motown singer's captivating depth – and a glimpse of the masterwork to come.