1. On p.67 Tseng means the Tensor product of representations.

2. On p.70 Tseng means the direct product of groups. Note however that the actual statement about the Lorentz group is wrong/imprecise as explained in e.g. this Phys.SE post.

3. See also my related Phys.SE answer here.

1. On p. 67 Tseng means a tensor product of representations.

2. On p. 70 Tseng means a direct product of groups.

Note however that the actual statement about the Lorentz group is wrong/imprecise as explained in e.g. this Phys.SE post.

Concerning direct product vs. tensor product of groups, see also my related Phys.SE answer here.