One starting place is this booklet you can find on our family website. It has a missionary story excerpt (really good one!) plus the beginnings of a booklist.
In addition to the titles listed on our PDF “Wonderful Missionary Books”, we are digging up links to older missionary books which you can read for free online! We hope they are a blessing to you!
Here are some stirring Missionary Quotes on a site with lots of links and leads to missionary material. (We don't share this brother's KJV only stance, but he has many profitable links.)
We hope to soon add links to more--
FREE missionary books online
Things as they are: mission work in Southern India by Amy Carmichael Very good!
Memoir of Mrs. Ann H Judson: Late Missionary to Burmah