Following to reference 1:
> "The sgRNA plasmid was co-injected with the single-stranded oligodeoxynucleotide (ssODN) donor template and the Cas9 protein into FVB/N zygotes to generate eleven F0 founders.
[...]
Double-strand breaks (DSB) were detected in 7 of 11 mice
[...]
The target region was sequenced, revealing that F0 3 and 5 incorporated the donor template precisely in 35.7% and 18.8% of somatic cells, respectively (Fig. 1c), while F0 7 and 8 incorporated indels in the integration, corroborating the unexpected results in the RFLP data.
[...]
A mixture of 3 ng/mL sgRNA plasmid, 3ng/mL of Cas9 protein (NEB Ipswich, MA), and 1mM ssODN (Integrated DNA Technologies, Iowa) was injected into the pronuclei and cytoplasm of FVB/N inbred zygotes. Zygotes that survived injection were transferred into oviducts of 0.5-day post-coitum, pseudopregnant B6xCBA F1 females and carried to term. The resulting gene-corrected mice were backcrossed, initially into the FVB/N background, to determine the germ-line transmission efficiency of the repair." https://www.ncbi.nlm.nih.gov/pubmed/27203441
This is missing some crucial info isn't it? How many FVB/N zygotes were injected to generate those 11 original mice?