This project would not have been possible without the help of the members of the LEO translators' forums.
A lot of my wisdom is taken from the following links:
About flat adverbs
Wikipedia: Flat adverb
"Flat adverbs are flat-out useful"
Merriam-Webster: Flat adverbs
"When adverbs fall flat"
"Flat adverbs are exceeding fine"
Drive safe - in praise of flat adverbs
Towson University: Adverbs
About adverbs in general
List of commonly used adverbs