Effect of single nucleotide deletion or insertion on primer annealing
We used this kind of primers to generate out of frame mutations or to add additional bases. In my experience your PCR will work (probably a a lower efficiency) and you will get a product with an additional base. We used primers with bigger differences in PCR based site directed mutagenesis of plasmids, there up to 10 bases didn't match but the primers where also longer. For single nucleotide mismatches (either + or - one base) we used primers around this size.

Regarding the literature, this publications might be useful:


A guide to the design and use of mismatched and degenerate
primers
Effects of primer-template mismatches on the polymerase chain
reaction: Human immunodeficiency virus type 1 model studies
The Effects of Internal Primer-Template Mismatches on RT-PCR: HIV-1
Model Studies
Effect of primer mismatch, annealing temperature and PCR cycle number
on 16S rRNA gene-targetting bacterial community analysis


Especially the first publication contains a lot of other interestings references.