The rules that use the vocabulary item "howitzers" are:

<i_f_v-pl>

122mm howitzers

152mm howitzers

2s1 122mm howitzers

2s1 howitzers

2s3 152mm howitzers

2s3 howitzers

swa 122mm howitzers

swa 152mm howitzers

swa 2s1 122mm howitzers

swa 2s1 howitzers

swa 2s3 152mm howitzers

swa 2s3 howitzers

<specific_vehicle_type-pl>

155mm howitzers

<i_f_v>

122mm howitzers

152mm howitzers

2s1 122mm howitzers

2s1 howitzers

2s3 152mm howitzers

2s3 howitzers

swa 122mm howitzers

swa 152mm howitzers

swa 2s1 122mm howitzers

swa 2s1 howitzers

swa 2s3 152mm howitzers

swa 2s3 howitzers

<specific_vehicle_type-not_creatable-pl>

155mm howitzers

<specific_vehicle_type-not_creatable>

155mm howitzers