Myriad/A myriad of

Myriad versus a myriad of at the Delta College WRIT Center's blog:
https://writcenterblog.wordpress.com/2015/09/15/myriad-vs-a-myriad-of/

Was/Were

 A post on 'was' versus 'were' at the Delta College WRIT Center's blog:

https://writcenterblog.wordpress.com/2015/09/15/waswere/

I–V–vi–IV

List of songs containing the I-V-vi-IV chord progression