"by written" is correct and usable in written English.
You can use it to indicate that a document is in written form. For example, "The agreement was signed by both parties, by written."
I was 11 years old when I heard "Get By", written by Talib Kweli.
Permit stockholders to act by written consent.
Regrades are by written petition only.
Produced by, directed by, written by, and starring.
Clearly define time frames, deadlines and compensations by written agreements.
In colour-graphemic synaesthesia, subjects report colour experiences induced by written letters.
Data were collected by written questionnaires from 197 advisory group members in 2001.
The Public has been in a defensive crouch, answering questions only by written statements.
Others have suggested that scores should be replaced by written narratives.
In this work we integrate UML class diagrams and OhCircus by written UML elements in terms of OhCircus constructs.
He denied reports that his resignation had been prompted by written threats against him.
