Examples:

• In a nation of more than 300 million people, this cannot be done by word of mouth alone.
• Names are meaningless and even ancient history has to be read with certain reservations, as it goes back to days when much was handed over only by word of mouth.
• The report may be made either by word of mouth or by letter.
• The truth will spread by word of mouth, if by no other means.
• The novel was the kind of book that circulates by word of mouth.
• At present, visits to the wetland are promoted by word of mouth by tourists.
• It was perpetuated by word of mouth as one priest told another what he knew.
• I found this job by word of mouth, one of my friends is working here, too.
• When the lease period is less than a month, the agreement may be by word of mouth.
• And no one doubts, that if the Songs should command by word of mouth, this would be their commandment.