Gilbert Strang (already mentioned by fellow commenters).
> The subject is too young
"The first modern and more precise definition of a vector space was introduced by Peano in 1888; by 1900, a theory of linear transformations of finite-dimensional vector spaces had emerged." (from Wikipedia)
The first book was written in 1942 - it's mentioned explicitly in LADR.
It doesn't mean the concepts didn't exist - they did, Frobenius even built a brilliant theory around them (representation theory), but the subject was defined quite loosely - apparently no one cared to collect the results in one place.
It doesn't even matter much: I remember taking the course in 1974, and it was totally different from what is being taught today.
Gilbert Strang (already mentioned by fellow commenters).
> The subject is too young
"The first modern and more precise definition of a vector space was introduced by Peano in 1888; by 1900, a theory of linear transformations of finite-dimensional vector spaces had emerged." (from Wikipedia)