  The Pevatron Test Statistic (PTS) is applied to data from $\gamma$-ray
observatories to test for the origin of Cosmic Rays (CRs) at energies around
the knee of the CR spectrum. Several sources are analyzed within hadronic
emission models. Previously derived results for RX J1713.7$-$3946, Vela Jr.,
and HESS J1745$-$290 are confirmed to demonstrate the concept, reliability, and
advantages of the PTS. It is excluded with a significance more than $5\sigma$
that the sources RX J1713.7$-$3946 and Vela Jr. are Pevatrons, while strong
indications exceeding $4\sigma$ are found for excluding HESS J1745$-$290 as a
Pevatron. The importance to resolve source confusion with high angular
resolution observations for Pevatrons searches is demonstrated using PTS for
the region containing the SNR G106.3+2.7 and the Boomerang nebula. No
statistically significant conclusion with respect to Pevatron associations
could be drawn from this region, for the diffuse $\gamma$-ray emission around
the Galactic Center, and the unidentified $\gamma$-ray sources LHAASO
J2108$+$5157, HESS J1702$-$420A and MGRO J1908$+$06. Assuming the entire
$\gamma$-ray emission from MGRO J1908+06 and the tail region of SNR G106.3+2.7
is hadronic, a statistical indication exceeding $3\sigma$ is found for the
underlying proton spectrum to extend beyond 350$-$400 TeV as a power-law. This
result can indicate that these sources are proton and helium Pevatrons, in
which the accelerated particles contribute to the knee of proton and helium
spectra observed at Earth.
